How can you possibly deny scientific proof? The Bible is like Mother Goose or fairy tales. If you actually believe in the stories of Noah or Jonah, then you should possibly commit yourself to a mental institution. I do believe that the Bible has done good for people. It teaches people morals and the right thing to do, but other than that it's just a book of make-believe, much like children's stories like Jack in the Beanstalk. According to the Bible, Adam and Eve had two sons. Cain and Abel. In order to produce more human beings, either Cane or Abel had sex with their mother. I feel silly even arguing with a person about this because it's so obviously phony. Please wake up. Realize that religion is a way of the past. Now people are smarter and scientists have proven the Bible to be completely inconsistent. I believe in the future more people will realize the truth. My mother and my older family all believe in the Bible. In this generation of cousins, none of us do. Hopefully, in the future, many generations from now, religion will be forgotten and the Bible will be a funny story we tell our little children.
"Since you have purified your souls in obeying the truth through the Spirit in sincere love of the brethren, love one another fervently with a pure heart, having been born again, not of corruptible seed but incorruptible, through the word of God which lives and abides forever, because "All flesh is as grass, And all the glory of man as the flower of the grass. The grass withers, And its flower falls away, But the word of the LORD endures forever." Now this is the word which by the gospel was preached to you" (I Peter 1:22-25).
The demise of Christianity has been predicted for hundreds of years, and such predictions will continue to fail until the end of the world.
"For since, in the wisdom of God, the world through wisdom did not know God, it pleased God through the foolishness of the message preached to save those who believe. For Jews request a sign, and Greeks seek after wisdom; but we preach Christ crucified, to the Jews a stumbling block and to the Greeks foolishness, but to those who are called, both Jews and Greeks, Christ the power of God and the wisdom of God. Because the foolishness of God is wiser than men, and the weakness of God is stronger than men. For you see your calling, brethren, that not many wise according to the flesh, not many mighty, not many noble, are called. But God has chosen the foolish things of the world to put to shame the wise, and God has chosen the weak things of the world to put to shame the things which are mighty; and the base things of the world and the things which are despised God has chosen, and the things which are not, to bring to nothing the things that are, that no flesh should glory in His presence" (I Corinthians 1:21-29).
It is amusing to see people attempt to argue by assertion. Science has not disproved the Bible. Most of the Bible is not in the measurable realm that science requires, but where it makes statements that can be verified, it has always been shown to be accurate. See earlier attempts at making this argument: "How can I believe the Bible when science has proven it wrong?" and "Why do people believe a text written by uneducated people when science has proven the Bible to be completely false?"
In your case, you are not arguing against the Bible but against your imperfect understanding of the contents of the Bible. The Bible names three sons of Adam and Eve (not two) and states there were additional children. "And Adam lived one hundred and thirty years, and begot a son in his own likeness, after his image, and named him Seth. After he begot Seth, the days of Adam were eight hundred years; and he had sons and daughters" (Genesis 5:3-4). The simple answer is that at the beginning, the siblings married each other.
It is interesting that you feel the need to go out of your way to argue against something you so confidently assert is a fantasy. One would think that you fear that its moral standards, which you agree are good, might be upheld.
"Why do You stand afar off, O LORD? Why do You hide in times of trouble? The wicked in his pride persecutes the poor; let them be caught in the plots which they have devised. For the wicked boasts of his heart's desire; he blesses the greedy and renounces the LORD. The wicked in his proud countenance does not seek God; God is in none of his thoughts. His ways are always prospering; Your judgments are far above, out of his sight; As for all his enemies, he sneers at them. He has said in his heart, "I shall not be moved; I shall never be in adversity." His mouth is full of cursing and deceit and oppression; under his tongue is trouble and iniquity. He sits in the lurking places of the villages; in the secret places he murders the innocent; his eyes are secretly fixed on the helpless. He lies in wait secretly, as a lion in his den; he lies in wait to catch the poor; he catches the poor when he draws him into his net. So he crouches, he lies low, that the helpless may fall by his strength. He has said in his heart, "God has forgotten; He hides His face; He will never see." Arise, O LORD! O God, lift up Your hand! Do not forget the humble. Why do the wicked renounce God? He has said in his heart, "You will not require an account." But You have seen, for You observe trouble and grief, to repay it by Your hand. The helpless commits himself to You; You are the helper of the fatherless. Break the arm of the wicked and the evil man; seek out his wickedness until You find none. The LORD is King forever and ever; the nations have perished out of His land. LORD, You have heard the desire of the humble; You will prepare their heart; You will cause Your ear to hear, to do justice to the fatherless and the oppressed, that the man of the earth may oppress no more" (Psalms 10:1-18).