Why did Catholicism start and when did it happen?

Answer:

Why Catholicism started is fairly straightforward. Man has a difficult time leaving something alone. There is a strong desire to modify things with the goal of "improving" things. This tendency is encouraged by Satan who wants to destroy the works of God. "Now the Spirit expressly says that in latter times some will depart from the faith, giving heed to deceiving spirits and doctrines of demons, speaking lies in hypocrisy, having their own conscience seared with a hot iron, forbidding to marry, and commanding to abstain from foods which God created to be received with thanksgiving by those who believe and know the truth" (I Timothy 4:1-3).

Fixing a time for when Catholicism started is a bit more difficult because we would have to settle on exactly what constitutes Catholicism. The Roman Catholic church is not at all like the Orthodox Catholic churches; yet, they were at one time a single group. Nor is Roman Catholicism of today like what it was even a hundred years ago. (For example, a hundred years ago all masses were said in Latin and to speak a mass in any other language would get the priest in grave trouble.) What we see as Roman Catholicism today is an accumulation of gradual changes in beliefs and practices.

Here is a list of when some key doctrines were introduced:

1. Having the water blessed before usage - A.D. 108-112
   • "Holy Water: In the Romish, as also in the Greek, Russian, and Oriental churches, denotes water blessed by a priest or bishop for certain religious uses. The theory of its first introduction seems to have been that water is a fitting symbol of purity, and accordingly, in most of the ancient religions, the use of lustral or purifying water not only formed part of the public worship, but also entered largely into the personal acts of sanctification prescribed to individuals. The Jewish law also prescribed this, and it was a practice held in common by many Pagan nations (compare Riddle, Christ. Ant. p. 725). The sprinkling of the hands and face with water before entering the sanctuary, still generally observed by the adherents to that law, was retained, or, no doubt, may have given rise to its adoption by the early Christian Church. But its use was certainly for a very different purpose. Thus bishop Marcellus ordered Equitius, his deacon, to sprinkle holy water, hallowed by him, in houses and churches, to exorcise devils, which is said to have been done also by pope Alexander I. Joseph, the converted Jew, Epiphanius says, used consecrated water in exorcism." [Cyclopedia of Biblical Thoeological and Ecclesiastical Literature, Strong and McClintock, p. 57]
   • Cavedoni announced that in a third- or fourth-century cemetery at Chiusi there was a small column which he thought must have supported a holy water font. Boldetti, who is always very cautious, claims to have found different fonts in the catacombs, some made of marble, others of terra-cotta, and still others of glass. [Catholic Encyclopedia, "Holy Water Fonts"]
   • In the sixth century Paulus Silentiarius, when describing the wonders of St. Sophia, about A. D. 590, mentions the presence of a phiala from which "water gushes noisily into the air, issuing from a bronze pipe with a force that banishes all evils, when in the month of golden tunies [January], during the night of the Divine initiation, the people draw in vessels an incorruptible water, as no pollution reaches it, even when, having been several years removed from its source, it is enclosed in the hollow of a pitcher and kept in their houses." [Catholic Encyclopedia, "Holy Water Fonts"]
2. Separation of the clergy (preachers and elders) from the laity (members) - early second century.
   • "The words 'priest,' 'priesthood' (heirus, hierateuma) are never applied in the New Testament to the office of the Christian ministry. All Christians are said to be priests (1 Peter 2:5-9; Apoc. V, 10)" [Catholic Dictionary, Addis and Arnold, p. 692].
   • "The priesthood evolved" [Catholic Encyclopedia, Vol. XII, p. 406, 415].
   • "The Apostolic Fathers abstain from any mention of a Christian priesthood" [Catholic Dictionary, Addis and Arnold, p. 693].
   • "In the apostolical Church no abstract distinction of clergy and laity, as to privilege or sanctity, was known; all believers were called to the prophetic, priestly, and kingly offices in Christ (1 Peter 5:3). The Jewish antithesis of clergy and laity was at first unknown among Christians; and it was “only as men fell back from the evangelical to the Jewish point of view” that the idea of the general Christian priesthood of all believers gave place, more or less completely, to that of the special priesthood or clergy (Neander, Church History, Torrey’s ed., 1, 194 sq.; Schaff, History of the Christian Church, 1, ch. 5; Gieseler, Church History, 1, § 52). So Tertullian, even (De Baptismo, c. 17, before he became a Montanist): “The laity have also the right to administer the sacraments and to teach in the community. The Word of God and the sacraments were by the grace of God communicated to all, and may therefore be communicated by all Christians as instruments of the divine grace. But the question here relates not barely to what is permitted in general, but also to what is expedient under existing circumstances. We may here use the words of St. Paul, ‘All things are lawful for men, but all things are not expedient.’ If we look at the order necessary to be maintained in the Church, the laity are therefore to exercise their priestly right of administering the sacraments only when the time and circumstances require it.” From the time of Cyprian, the father of the hierarchical system, the distinction of clergy and laity became prominent, and very soon was universally admitted." [Cyclopedia of Biblical Thoeological and Ecclesiastical Literature, Strong and McClintock, p. 8]
   • "Since, according to my opinion, the grades here in the Church, of bishops, presbyters, deacons, are imitations of the angelic glory, and of that economy which, the Scriptures say, awaits those who, following the footsteps of the apostles, have lived in perfection of righteousness according to the Gospel. For these taken up in the clouds, the apostle writes, will first minister [as deacons], then be classed in the presbyterate, by promotion in glory (for glory differs from glory) till they grow into 'a perfect man.'" [Clement of Alexandria, Stromata, 13 (A.D. 202)]
   • "If anyone saith that all Christians have power to administer the word ... let him be anathema." [Canon X Council of Trent]
3. Special days set aside for fasting (leads to the practice of Lent) - A.D. 140
   • The dispute is not only about the day, but also about the actual character of the fast. Some think that they ought to fast for one day, some for two, others for still more; some make their ‘day’ last 40 hours on end. Such variation in the observance did not originate in our own day, but very much earlier, in the time of our forefathers.
     [Eusebius, History of the Church, V, 24]
   • In the early centuries, Lent was a time of preparation for those who would be baptized at the Easter vigil, the main time individuals were baptized in those days, Baltes said. He emphasized that the dying and rising aspect is central in the ritual of baptism because, "In baptism, we die and rise with Jesus."
     According to Baltes, the early Lenten season only lasted two or three days and those who would be baptized fasted in order to purify their bodies of sin. Gradually the time period expanded, depending on the time and place, and by the fourth century, the church had established its current 40-day Lenten season.
     [A look back at the history of Lenten practices by Kelley Kepler]
   • Around the fifth century, when the practice of infant baptism became more the norm, "Lent evolved as a period of penance for public sinners and for those who wanted re-admittance to the church," Baltes said. The most notorious public sins of the time were murder, adultery and apostasy -- the sin of denying the faith.
     [A look back at the history of Lenten practices by Kelley Kepler]
   • The celebration of Christ's resurrection on Easter Sunday became the primary feast of the year at a fairly early date. Christians fasted to prepare for the vigil of Holy Saturday. They also had maintained a fast on Fridays for some time when these two fasts were joined together to help people prepare for the vigil.
     [A Brief History of Lent]
   • When Rufinus translated this passage [the quote from Eusebius above] from Greek into Latin, the punctuation made between "40" and "hours" made the meaning to appear to be "40 days, twenty-four hours a day." The importance of the passage, nevertheless, remains that since the time of "our forefathers" — always an expression for the apostles — a 40-day period of Lenten preparation existed. However, the actual practices and duration of Lent were still not homogeneous throughout the Church.
     [History of Lent]
   • "... the 5th century historian, Socrates... describes a fast of three consecutive weeks before Easter... These three weeks of Lent, directly linked to the catechumenate in Rome, develop into a fast of forty days by the 4th century..." [Lizette Larson-Miller, "Lent" in The New Dictionary of Sacramental Worship, p. 681]
4. Regional elders began meeting - second century
   • "The first bishops were generally bishops of individual churches. In the larger cities, a number of congregations may have been under a single bishop, but these congregations were regarded as branches of the one city church. Each separate community had, as a rule, its own bishop. This is sufficiently proved by the great number of bishops found within a given territory. From the small province of proconsular Asia, forty--two bishops were present at an early council." [Henry C. Sheldon, History of the Christian Church, Vol 1, p 146].
   • "Councils and Dioceses: We first hear of the bishops from local congregations in the same province meeting for consultation in the second half of the second century in connection with the problem posed by Montanism. These meetings were first held in connection with common problems but became regular gatherings. As churches in the large cities grew, presbyters (elders) were assigned to particular assemblies within the city. Earlier all congregational functions had been under the supervision of the bishop. Increasingly these had to be assigned to the presbyters. Christians living in outlying areas would not have their own bishop but would look to the city church for leadership. Thus the basis was laid for the bishop to preside over several assemblies, although in theory all remained one church. The territory presided over by a bishop is now called a diocese." [Everett Ferguson, Early Christians Speak, p 16].
5. Babies are baptized - A.D. 180
   • "The Bible is silent or at least is not clear on a number of matters such as baptism of infants and the exact number of the sacraments, concerning which the Church follows tradition." [National Catholic Almanac, 1943, p. 128].
   • "Ecclesiastical custom with regard to the administration of Baptism has undergone a change in the course of history. Whereas the early Church baptized adults only, the baptism of children soon became the usual practice." [Pastoral Medicine, Ruland-Ratter, pp. 32-33].
   • "At the end of the second or beginning of the third century Tertullian refers to the responsibilities assumed by sponsors in baptism and represents their office as already and ancient institution." [De Baptismo C. XVIII]
   • "And they shall baptize the little children first. And if they can answer for themselves, let them answer. But if they cannot, let their parents answer or someone from their family." [Hippolytus of Rome, Apostolic Tradition, p. 21 (c. A.D. 215)]
   • "Therefore children are also baptized." [Origen, Homily on Luke, XIV (A.D. 233)]
   • "For this reason, moreover, the Church received from the apostles the tradition of baptizing infants too." [Origen, Homily on Romans, V:9 (A.D. 244)]
6. Making the sign of the cross when praying - late second century
   • There is positive evidence that the early Church Fathers practiced this in the early second century, as Tertullian, born AD 150, noted (De cor.Mil.,iii) said, "In all our travels and movements, in all our comings in and out, in putting of our shoes, at the bath, at the table, in lightning our candles, we mark our forehead with the sign of the cross." He even spoke about the Christian woman who use this for "signing of her bed", before retiring to rest. Epiphanus tells of a certain holy man (Adv. Haer.,xxx 12) called Josephus, who imparted on a vessel of water the power to overcome magical incarnations by "making over the vessel with his finger the sign of the cross". St Cyril of Jerusalem also of the early second century in his "Catecheses (xiii, 36) remarks "Let us not be ashamed to confess the crucified. Be the Cross our seal, made with boldness by our fingers on our brow; before we sleep; when we lie down, when we are traveling, and when we are at rest." ["What is the origin of the sign of the cross?", Catholic Straight Answers, 2022]
7. Belief in purgatory - A.D. 230
   • Tertullian lived around the end of the second century and the beginning of the third. He mentions in his work "De corona militias" that praying for the dead is an Apostolic ordinance. He tells a widow to pray for the repose of her husband's soul in "De Monogamia".
   • Cyprian said, "Our predecessors prudently advised that no brother, departing this life, should nominate any churchman as his executor; and should he do it, that no oblation should be made for him, nor sacrifice offered for his repose"
   • Clement of Alexandria who lived died in 215 A.D. and is quoted as saying, "the believer through discipline divests himself of his passions and passes to the mansion which is better than the former one, passes to the greatest torment, taking with him the characteristic of repentance for the faults he may have committed after baptism. He is tortured then still more, not yet attaining what he sees others have acquired. The greatest torments are assigned to the believer, for God's righteousness is good, and His goodness righteous, and though these punishments cease in the course of the expiation and purification of each one.."
   • "As for certain lesser faults, we must believe that, before the Final Judgment, there is a purifying fire. He who is truth says that whoever utters blasphemy against the Holy Spirit will be pardoned neither in this age nor in the age to come. From this sentence we understand that certain offenses can be forgiven in this age, but certain others in the age to come." [Gregory the Great]
   • "From the beginning the Church has honored the memory of the dead and offered prayers in suffrage for them, above all the Eucharistic sacrifice, so that, thus purified, they may attain the beatific vision of God." [Council of Lyons II, 1274 A.D.]
8. Pouring accepted as an alternative for baptism for the sick and others who had special needs - A.D. 257
   • The first recorded case of sprinkling was in 257 AD to someone on a sick-bed. It was then an exception to the rule and brought about fierce opposition from the whole church. Not until 757 AD did the church accept sprinkling in such sick-bed cases of necessity. It wasn't until 1311 AD, when the Catholic council of Ravenna, declared that sprinkling was and acceptable substitute for immersion and from that time forward sprinkling replaced immersion in the Roman Catholic church. [bible.ca]
   • "The present mode of pouring arose from the inconvenience connected with immersion, frequent mention of which is made in writings of the early Church fathers." [Question Box, p. 366].
9. Head of regional elders called bishop - third century
   • "It was ruled that hereafter there could not be more than one bishop in a city" [Decrees of the Nicene Council, Canon 8, p. 34].
   • "It is easily conceivable that the office of bishop grew up by a gradual development, which had its starting point in the board of presbyters. This board in the several churches would naturally come to have its presiding officer. Men of the greatest energy and ability would be called to fill this position. The interests of unity and efficient management would cause more and more power to be delegated to them, until they should become really the chiefs of the churches, or bishops proper. Analogy also may be quoted in favor of this theory. Other stages in the growth of the hierarchy were effected much in the manner here indicated for the first stage. By gradual advances, one bishop over-topped the other bishops in his neighborhood, and finally assumed toward them the relation of archbishop. Even among the deacons distinctions grew up, and one of the body in the different churches became known as the archdeacon. Surely it is no far-fetched suggestion, that a similar development raised one of the early presbyters in the various congregations to the rank of arch-presbyter, and then carried him over the short interval between that and the primitive bishop. That episcopacy originated in this way, is the conclusion of not a few scholars, even in a Church which has made much of apostolic succession. Bishop Lightfoot says of the evidences in the case, 'They show that the episcopate was created out of the presbytery.'" [Henry C. Sheldon, History of the Christian Church, Vol 1, p 143]
10. Constantine calls for a council, starting the joining of church and state - A.D. 325
11. Celebration of Easter - A.D. 325
    • "The observance of any non-Jewish special holiday throughout the Christian year is believed by some to be an innovation postdating the Early Church. The ecclesiastical historian Socrates Scholasticus (b. 380) attributes the observance of Easter by the church to the perpetuation of local custom, "just as many other customs have been established," stating that neither Jesus nor his Apostles enjoined the keeping of this or any other festival. However, when read in context, this is not a rejection or denigration of the celebration-which, given its currency in Scholasticus' time would be surprising-but is merely part of a defense of the diverse methods for computing its date. Indeed, although he describes the details of the Easter celebration as deriving from local custom, he insists the feast itself is universally observed. Perhaps the earliest extant primary source referencing Easter is a 2nd century Paschal by Melito of Sardis, which characterizes the celebration as a well-established one. [Wikipedia]
12. Confessing of sins to a priest - A.D. 374
    • "Auricular confession is nowhere expressly mentioned in the Bible" [Question Box, 1929, p. 287].
    • In a prayer consecrating a bishop: "And that by the high priestly Spirit he may have authority to forgive sins" [Hippolytus, Apostolic Tradition, 3 (A.D. 215)]
    • "It is necessary to confess our sins to those whom the dispensation of God's mysteries is entrusted." [Basil, Rule Briefly Treated, 288 (A.D. 374)]
    • "The mitigation of public penance is first indicated in a letter of Pope St. Innocent in the year 405. A similar trend of leniency is found in the East at the turn of the fifth century. One reason is due to the scandals which were sometimes consequent to public penance. For about a thousand years, there were modifications of the ancient usage. By the middle of the sixteenth century, public penance had practically disappeared." [Brooklyn Tablet, Jan. 20, 1962].
    • Leo the Great (440-461 A.D.) "forbade public confession." [Lives and Times of the Roman Pontiffs, Chevalier Artaud de Montor, Vol. I, p. 103].
    • "Still the doctrine was not fully established in the West till the time of Gregory the Great." [Catholic Dictionary, Addis and Arnold, p. 706].
13. Bishops from major cities called archbishops - fourth century
    • "The divine institution of the threefold hierarchy cannot of course be derived from our text; in fact it cannot in anyway be proved directly from the New Testament; it is a Catholic dogma by virtue of the dogmatic traction, i.e. in a later period of ecclesiastical history the general belief in the divine institution of the episcopate, presbyteriate, and diconate can be verified and thence followed through the centuries. But the dogmatic truth cannot be traced back to Christ Himself by analysis of strict historical testimony." [Catholic Encyclopedia, Vol. VII, p. 334].
    • "Catholic theologians do not deny that the double "hierarchy of order and jurisdiction" gradually developed from the germ already existing in the primitive Church, just as the primacy of the pope of Rome and especially the distinction of simple priests from the bishops was recognized with increasing clearness as time advanced" [Catholic Encyclopedia, Vol. XII, p. 415].
    • "At the end of the fifth century the Roman Church was completely organized." [Catholic Encyclopedia, Vol. XI, p. 61].
14. Monastic orders - Fourth and fifth century
    • "St. Anthony of Egypt (251-356) is considered by some to be the father of Christian monasticism. He lived the life of an ascetic, sheltered in the tombs outside of Alexandria, Egypt, in the second half of the third and first half of the fourth centuries." [Doug Archer, "Monasticism still thrives after 1,700 years," Catholic Register, 6 March 2008.]
    • "A young man named Benedict (480-547) abandoned his life of wealth and privilege in a morally decaying Rome and went in search of the kind of pious existence exemplified in the Gospels. For years he took refuge in a cave, living a life of discipline, prayer and contemplation. In time, Benedict, who would later be canonized, established a community of monks based on a set of rules of conduct that focused on devotion to God. What would be known as The Rule of St. Benedict became the foundation for monasticism and monastery life within the Catholic Church and played a crucial role in the expansion of Christianity throughout Europe." [Doug Archer, "Monasticism still thrives after 1,700 years", Catholic Register, 6 March 2008]
    • "The monks first introduced the tonsure, i.e., the practice of shaving the head, and during the seventh century this was adopted by the clergy generally." [Short History of the Catholic Church, Wedewer and McSorley, p. 69].
15. Transubstantiation, the belief that the elements of the Lord’s Supper become the literal body and blood of Christ - A.D. 350
    • "Having learn these things, and been fully assured that the seeming bread is not bread, though sensible to taste, but the Body of Christ; and that the seeming wine is not wine, though the taste will have it so, but the Blood of Christ; and that of this David sung of old, saying, And bread strengtheneth man's heart, to make his face to shine with oil, 'strengthen thou thine heart,' by partaking thereof as spiritual, and "make the face of thy soul to shine." [Cyril of Jerusalem, Catechetical Lectures, XXII:8 (c.A.D. 350)]
    • "The term transubstantiation seems to have been first used by Hildebert of Tours (about 1079). His encouraging example was soon followed by other theologians, as Stephen of Autun (d. 1139), Gaufred (1188), and Peter of Blois (d. about 1200), whereupon several ecumenical councils also adopted this significant expression, as the Fourth Council of the Lateran (1215), and the Council of Lyons (1274), in the profession of faith of the Greek Emperor Michael Palæologus. The Council of Trent (Sess. XIII, cap. iv; can. ii) not only accepted as an inheritance of faith the truth contained in the idea, but authoritatively confirmed the "aptitude of the term" to express most strikingly the legitimately developed doctrinal concept." [Catholic Encyclopedia]
16. The mass replaces the Lord’s Supper - A.D. 350
    • Etychianus [275-283 AD] "According to Bury [Romanor, Ponitific, brevis notitia, 1726, p. 30], this pope instituted the Offertory of the Mass; and he ordered the benediction, under certain circumstances, of branches of trees and of fruit." [The Life and Times of the Roman Pontiffs, Chevalier Artaud de Montor].
    • The use of Latin exclusively occurred in the mid-300s [Catholic Encyclopedia, "Canon of the Mass: History of the Canon"]
    • "The first certain use of it [Mass] is by St. Ambrose [who died in A.D. 397]." [Catholic Encyclopedia, Vol. IX, p. 791].
17. The celebration of Christmas - A.D. 360
    • "It is said that Julius I [337-352 A.D.] ordered the feast of Christmas to be kept on 25th of December. Pagi (see Breviar. Pont. Rom.) is of that opinion; but in the very ample collection of the councils (Vol. ii., p. 1255) it is show that the institution of the celebration of that great feast of of a later date than the pontificate of Julius." [The Life and Times of the Roman Pontiffs, Chevalier Artaud de Montor].
18. Theodosius declares Christianity to be the state religion - A.D. 380
19. Special vestments for clergy - fifth century.
    • "During the first four or five centuries the dress of clerics did not differ from that of the laity either in form or color." [General Legislation in the New Code of Canon Law, Ayrinhac, p. 290].
    • "It is thought by Mr. Marriott (Festiariuns Christianum) that most of the vestments now in use were introduced into the Church during the period between the 9th and 12th centuries." [Cyclopedia of Biblical Theological and Ecclesiastical Literature, Strong and McClintock]
20. The doctrine of inherited sins, salvation by faith only, and once saved always saved - A.D. 400
    • "Where in the fourth and fifth centuries the doctrine of original sin became better known, the practice of infant baptism progressed rapidly." [Legislation on the Sacraments in the New Code of the Canon Lay, Ayrinhac, p. 72].
21. Candles are used in worship as a sacred element - A.D. 417
    • "We need not shrink from admitting that candles, like incense and lust-al water, were commonly employed in pagan worship and in the rites paid to the dead. But the Church from a very early period took them into her service, just as she adopted many other things indifferent in themselves, which seemed proper to enhance the splendour of religious ceremonial. We must not forget that most of these adjuncts to worship, like music, lights, perfumes, ablutions, floral decorations, canopies, fans, screens, bells, vestments, etc. were not identified with any idolatrous cult in particular; they were common to almost all cults. They are, in fact, part of the natural language of mystical expression, and such things belong quite as much to secular ceremonial as they do to religion." [Catholic Encyclopedia, "Candles," Volume III.]
22. Veneration of Mary as the mother of God - A.D. 470
    • Celestine I (422-4320) was "First to call Mary 'Mother of God.'" [Lives and Times of the Roman Pontiffs, Chevalier Artaud de Montor, Vol. I, p. 98].
23. Veneration and bowing to images of saints - A.D. 500
    • "The council [Second Council of Nicaea in A.D. 787] uses the word proskunei of the veneration due to images." [Catholic Dictionary, Addis and Arnold, p. 423].
24. Extreme Unction, the anointing of the dying or dead for spiritual forgiveness - A.D. 528
    • "O God who sanctifiest this oil as Thou dost grant unto all who are anointed and receive of it the hallowing wherewith Thou didst anoint kings and priests and prophets, so grant that it may give strength to all that taste of it and health to all that use it."
      [Hippolytus of Rome, Apostolic Tradition, 5:2 (c.A.D. 215)]
    • "In the epistle of the blessed Apostle James...'If anyone among you is sick, let him call the priests...'. There is no doubt that this anointing ought to be interpreted or understood of the sick faithful, who can be anointed with the holy oil of chrism...it is a kind of sacrament." [Pope Innocent (A.D. 401-416), To Decentius (A.D. 416)].
    • "A priest is to be called in, who by the prayer of faith and the unction of the holy oil which he imparts will save him who is afflicted [by a serious injury or by sickness]." [Cassiodorus, Complexiones (A.D. 570), in Catholic Encyclopedia,Vol. V p. 720].
25. Gregory I became archbishop of Rome which was declared the center of the universal church - A.D. 590
    • "Gregory found it necessary to repress a claim of John the Faster, a man, however, whom the Greeks represent as a prelate of such great virtue (Novaes, i., p. 242), that he was placed among the number of saints, a step to which the approval of the congregation of the Propaganda was given afterwards. John assumed the title of the Universal Bishop. The predecessor of Gregory had censured that title; and Gregory had already deprived Eulogus, bishop of Alexandria of the similar title of Universal Patriarch." [The Life and Times of the Roman Pontiffs, Chevalier Artaud de Montor, p. 139].
    • "Saint Gregory was also the first pontiff who employed the phrase to speak ex cathedra." [The Life and Times of the Roman Pontiffs, Chevalier Artaud de Montor, p. 139].
    • "Almost all the leading principles of later Catholicism are found, at any rate in germ, in Gregory the Great" [Catholic Encyclopedia, Vol. VI, p. 780].
26. Boniface III accepts the title of Pope - A.D. 606
    • "At first this name [pope] was applied in common to all priests, whence came the custom of giving the name of father to every regular priest. Then the name was given only to bishops. Papebrok (in Conat. Chrono. History. ad Siricium, p. 147, No. 9), says that Saint Siricius was the first who called himself papa (pope), and that he so styles himself in many letters which he wrote to various provinces. Saint Leo the Great elected in 440, follows that example; in his Epistle. 17, he entitles himself 'Leo, Papa Universis per Sicilium constitutis Salutem.' At the end of the ninth century, this name was no longer given to anyone but the sovereign pontiffs of Rome." [The Life and Times of the Roman Pontiffs, Chevalier Artaud de Montor, p. 90].
    • "Leo was the first to state the Petrine doctrine outright, saying that he was the "heir" of St. Peter and that Christ had appointed Peter as head of his church. He said that all bishops were heirs to the apostles (this was general belief at the time), and that Peter was the chief of the apostles. The Bishop of Rome was, therefore, the chief of all bishops." [The Orb: Online Reference Book for Medieval Studies, "The Papacy"]
    • "The See of Blessed Peter, the Apostle, should be the head of all the churches, and that the title of Universal Bishop belonged exclusively to the Bishop of Rome." [Catholic Encyclopedia, "Emperor Phocas for Boniface III," Vol. II, p. 660]
27. Organ was introduced into worship but removed when a division was threatened - A.D. 670
    • "During the time he [Vitalian 657-672 A.D.] was pope instrumental music was introduced in the Catholic Church." [Lives and Times of the Roman Pontiffs, Vol. I, p. 162].
28. Organ reintroduced and remained - A.D. 775
29. Canonization of Saints - Tenth Century
    • "Canonization, the process the Church uses to name a saint, has only been used since the tenth century. For hundreds of years, starting with the first martyrs of the early Church, saints were chosen by public acclaim. Though this was a more democratic way to recognize saints, some saints' stories were distorted by legend and some never existed. Gradually, the bishops and finally the Vatican took over authority for approving saints." [Frequently Asked Questions about Saints].
    • "At a Roman synod held in Lateran on 31 January, 993, Bishop Ulric of Augsburg was solemnly canonized, an event which the pope announced to the French and German bishops in a Bull dated 3 February. This was the first time that a solemn canonization had been made by a pope." [Catholic Encyclopedia, Vol. VIII, p. 428].
30. Establishment of Lent and Good Friday. Fasting on Fridays and during Lent - A.D. 998
31. Penance instituted - A.D. 1022
32. Pope Leo IX excommunicated Michael Cerularius, the archbishop of Constantinople, causing the formation of the Eastern Orthodox Church - A.D. 1053
33. Prohibition of the clergy to marry - 1079 A.D.
    • In 1079 AD celibacy was first enforced for priests and bishops by Pope Gregory VII. Before this time, they were permitted to marry. [bible.ca]
    • After the Lateran Council (A.D. 1123), "... henceforth all conjugal relations on the part of the clergy ... were reduced in the eyes of Canon Law to mere concubinage" (Catholic Encyclopedia, Vol. III, p. 486).
    • "The Council of Trent (about A.D. 1550) affirmed as a matter of faith that it [celibacy] is holier than marriage." [Externals of the Catholic Church, Sullivan, p. 305]
34. Rosary beads introduced - A.D. 1090
    • Catholics pray repetitive words with Rosary Beads that were first invented in 1090 AD, by "Peter the Hermit" and made popular by St. Dominic in 1208 AD. Catholics believe that Mary appeared to St. Dominic in 1208 AD, at the church of Prouille and revealed the Rosary Beads to him. [bible.ca]
35. Sprinkling accepted as a form of baptism for all people - A.D. 1311
    • "Catholics admit that immersion brings out more fully the meaning of the sacrament, and that for twelve centuries it was the common practice." [Question Box, p. 240].
    • "Immersion still prevails among the Copts and Nestorians, and for many ages, baptism was so given among the Latins also for even St. Thomas, in the thirteenth century, speaks of baptism by immersion as the common practice of his time." [Catholic Dictionary, Addis and Arnold, p. 60].
36. Laity does not partake of the cup in Mass - A.D. 1414
    • About this time [a thousand years after the New Testament] the wine was taken from the laity and given to the priests. At which time the priest was authorized to spike the wine to 18 percent or 36 proof. [Catholic Encyclopedia, Vol. III, p. 562].
    • Two early popes condemned withholding the cup, (Pope Leo I [died 461 AD] and Pope Gelasius [died 496 AD]; but in the 12th century the practice was begun, and formally approved by the Catholic Council of Constance in 1415 AD. So for the first 1000 years, the Catholics in the pews drank the cup, then the Pope changed this apostolic tradition. [bible.ca]
37. Purgatory proclaimed as a dogma at the Council of Florence - A.D. 1438
38. Tradition declared to be equal to the authority of the Bible at the Council of Trent - A.D. 1545
39. Mass to be said universally in Latin - A.D. 1546
40. Apocryphal books added to the Bible by the Council of Trent - A.D. 1546
41. Confirmation begins - A.D. 1547
42. Mardi Gras attendees granted plenary indulgence - A.D. 1747
    • "The Church repeatedly made efforts to check the excesses of the carnival , especially in Italy. During the sixteenth century in particular a special form of the Forty Hours Prayer was instituted in many places on the Monday and Tuesday of Shrovetide, partly to draw the people away from these dangerous occasions of sin, partly to make expiation for the excesses committed. By a special constitution addressed by Benedict XIV to the archbishops and bishops of the Papal States, and headed "Super Bacchanalibus" , a plenary indulgence was granted in 1747 to those who took part in the Exposition of the Blessed Sacrament which was to be carried out daily for three days during the carnival season." [Catholic Encyclopedia, "Shrovetide"].
43. Immaculate conception of Mary - A.D. 1845
    • "The Lord Jesus Christ alone among the sons of men was born immaculate" [Pope Leo I, A.D. 440, Sermon 24 in Nativ. Dom.]
    • "It belongs alone to the Immaculate Lamb to have no sin at all" [Pope Gelasius, A.D. 492, Gelassii Pape Dicta, Vol. 4, col 1241, Paris, 1671]
    • "She [Eve] was produced without sin, but she brought forth in sin; she [Mary] was produced in sin, but she brought forth without sin." [Pope Innocent III, A.D. 1216, De Festo Assump., sermon 2].
    • "We, by the authority of Jesus Christ, our Lord, of the Blessed Apostles, Peter and Paul and by our Own, declare, pronounce, and define that the doctrine which holds that the Blessed Virgin Mary, at the first instant of her conception, by a singular privilege and grace of the omnipotent God, in consideration of the merits of Jesus Christ, the Savior of mankind was preserved free from all stain of original sin, has been revealed by God, and therefore is to be firmly and constantly believed by all the faithful." [Pope Pius IX, December 8, 1854].
44. Infallibility of Pope - A.D. 1870
    • "Saint Gregory was also the first pontiff who employed the phrase to speak ex cathedra." [The Life and Times of the Roman Pontiffs, Chevalier Artaud de Montor, p. 139].
    • "That apostolic primacy which the Roman pontiff possesses as successor of Peter, the prince of the apostles, includes also the supreme power of teaching. This holy see has always maintained this, the constant custom of the church demonstrates it, and the ecumenical councils, particularly those in which East and West met in the union of faith and charity, have declared it....Indeed, their apostolic teaching was embraced by all the venerable fathers and reverenced and followed by all the holy orthodox doctors, for they knew very well that this see of St. Peter always remains unblemished by any error, in accordance with the divine promise of our Lord and Saviour to the prince of his disciples...." [First Vatican Council, 1870].
45. Bodily assumption of Mary proclaimed by Pius Xii - A.D. 1950
46. Limbo, the place for unbaptized babies who die, was demoted from a firm belief to a theological theory by a Vatican council - A.D. 2007

Most people fix the beginning to the first man to accept the title of Pope: Boniface III in A.D. 606, but many things happened that led up to that event. And many changes have taken place since then.

Since writing the list above, several people have asked for the sources of these dates. The problem in fixing dates to changes is that most were gradually introduced. Most of the dates above are when the ideas were either first recorded or made official by some decree.