When the Lord referred to "the Son of Man coming in His kingdom" (NKJV) is he referring to coming in Judgment or His return?
To fully understand what Jesus said, we need to examine all three records of this particular teaching:
"For the Son of Man will come in the glory of His Father with His angels, and then He will reward each according to his works. Assuredly, I say to you, there are some standing here who shall not taste death till they see the Son of Man coming in His kingdom" (Matthew 16:27-28).
""For whoever is ashamed of Me and My words in this adulterous and sinful generation, of him the Son of Man also will be ashamed when He comes in the glory of His Father with the holy angels." And He said to them, "Assuredly, I say to you that there are some standing here who will not taste death till they see the kingdom of God present with power"" (Mark 8:38-9:1).
"For whoever is ashamed of Me and My words, of him the Son of Man will be ashamed when He comes in His own glory, and in His Father's, and of the holy angels. But I tell you truly, there are some standing here who shall not taste death till they see the kingdom of God" (Luke 9:26-27).
At the Beginning of His Kingdom
Despite his humiliation and death, Jesus would come into God’s glory. "Therefore God also has highly exalted Him and given Him the name which is above every name, that at the name of Jesus every knee should bow, of those in heaven, and of those on earth, and of those under the earth, and that every tongue should confess that Jesus Christ is Lord, to the glory of God the Father" (Philippians 2:9-11). The coming in the glory of the Father and the coming in His kingdom refer to the same event. It is an allusion to Daniel's prophecy. "I was watching in the night visions, and behold, One like the Son of Man, coming with the clouds of heaven! He came to the Ancient of Days, and they brought Him near before Him. Then to Him was given dominion and glory and a kingdom, that all peoples, nations, and languages should serve Him. His dominion is an everlasting dominion, which shall not pass away, and His kingdom the one Which shall not be destroyed" (Daniel 7:13-14).
Preterism sees the "Son of Man coming" and say that this is a reference to the destruction of Jerusalem. But notice that the verse does not state where Jesus went to come into his glory and kingdom. In English, we see "come" and assume it means coming to us, though it doesn't always mean this. In Greek "erchomai is a general word expressing motion. The motion may either be toward the speaker (in which case it means "come") or away from the speaker (in which case it means "go"). English has two separate words to express these ideas, but Greek can use the same word" [Complete Biblical Library Greek - English Dictionary]. Daniel's prophecy makes it clear that it took place in heaven before the throne of God. He came, not to the prophet or those seeing the arrival of the kingdom, but he came to God the Father.
If this was speaking of the destruction of Jerusalem, then there is a problem because the kingdom began before Jerusalem was destroyed. Stephan at his death saw Jesus in the glory of his Father. "But he, being full of the Holy Spirit, gazed into heaven and saw the glory of God, and Jesus standing at the right hand of God" (Acts 7:55). That moment was years before the destruction of Jerusalem. Paul talked of the kingdom as existing. "He has delivered us from the power of darkness and conveyed us into the kingdom of the Son of His love" (Colossians 1:13). Notice the use of the past tense. When we are saved from sin, we are delivered into the kingdom.
There really isn't anything in these verses or their context that refer to the destruction of Jerusalem. It is inserted there by those who believe in Preterism, but nothing in the verses would bring the destruction of Jerusalem to mind. Further, we established that the glory and the kingdom came to Jesus prior to the destruction of Jerusalem. Therefore, what we must conclude is that these verses do not support preterism.
At the End of His Kingdom
Paul also stated that Jesus was ruling and that rule would continue until death is destroyed. "For as in Adam all die, even so in Christ all shall be made alive. But each one in his own order: Christ the firstfruits, afterward those who are Christ's at His coming. Then comes the end, when He delivers the kingdom to God the Father, when He puts an end to all rule and all authority and power. For He must reign till He has put all enemies under His feet. The last enemy that will be destroyed is death" (I Corinthians 15:22-26). Since death still continues to this day, the coming in I Corinthians 15:23 must be different from Christ's coming into his kingdom. One refers to the start of his kingdom and the other to the end of his reign. So now we've added another consideration: Is it possible that Jesus is referring to two different events, one being the start of his kingdom and the other being the end?
Many of Jesus' illustrations were about going far away and to return at some later, unspecified time.
"Hear another parable: There was a certain landowner who planted a vineyard and set a hedge around it, dug a winepress in it and built a tower. And he leased it to vinedressers and went into a far country" (Matthew 21:33).
"For the kingdom of heaven is like a man traveling to a far country, who called his own servants and delivered his goods to them" (Matthew 25:14).
"It is like a man going to a far country, who left his house and gave authority to his servants, and to each his work, and commanded the doorkeeper to watch. Watch therefore, for you do not know when the master of the house is coming--in the evening, at midnight, at the crowing of the rooster, or in the morning-- lest, coming suddenly, he find you sleeping. And what I say to you, I say to all: Watch!" (Mark 13:34-37).
"A certain nobleman went into a far country to receive for himself a kingdom and to return" (Luke 19:12).
"Then He began to tell the people this parable: "A certain man planted a vineyard, leased it to vinedressers, and went into a far country for a long time"" (Luke 20:19).
The implication is that there would be time between receiving the kingdom and his eventual return.
Jesus said that some would not taste death until they saw Jesus coming into his kingdom. That implies they would die afterward. It cannot be a reference to the end of the kingdom since death continues. Thus, we realize that some would not death before they witnessed the beginning of Jesus' kingdom.
What about the rewarding of each man according to his works? If we say it was at the beginning of the kingdom, then the rewarding was limited to only a few since the kingdom just began. But Paul, who said the kingdom was in existence said, "But in accordance with your hardness and your impenitent heart you are treasuring up for yourself wrath in the day of wrath and revelation of the righteous judgment of God, who "will render to each one according to his deeds"" (Romans 2:5-6). Paul saw reward as being in the future from when he spoke. It was a single day, yet to come. It could not have already taken place at the beginning. Nor was it seen as a limited rewarding, but a universal one. "For we must all appear before the judgment seat of Christ, that each one may receive the things done in the body, according to what he has done, whether good or bad" (II Corinthians 5:10).
"For as the Father has life in Himself, so He has granted the Son to have life in Himself, and has given Him authority to execute judgment also, because He is the Son of Man. Do not marvel at this; for the hour is coming in which all who are in the graves will hear His voice and come forth--those who have done good, to the resurrection of life, and those who have done evil, to the resurrection of condemnation" (John 5:26-29). The use of "hour" in Jesus' statement indicates that it is a single event, not something drawn out over the age. At that time there will be a judgment of all who have died, good and evil.
The prospect of facing judgment was not limited just those who lived before Jerusalem's destruction. "And as it is appointed for men to die once, but after this the judgment, so Christ was offered once to bear the sins of many. To those who eagerly wait for Him He will appear a second time, apart from sin, for salvation" (Hebrews 9:27-28). It is a universal truth that everyone dies, and after death comes the judgment. That judgment, the writer of Hebrews says, is at Jesus second appearing. Since those are currently dying will be facing judgment, that means Jesus second appearing has yet to take place.
So What Was Jesus Saying?
Jesus was giving a promise that there would be a future judgment. A promise that we realize from other verses would be a long time in coming. How do we, or those hearing Jesus, know that this distant promise would be kept? Jesus offered a second promise that would be fulfilled in the immediate future -- seeing the kingdom come in power. When they received that promise, all would be confident that the first promise -- Jesus's coming, judgment, and reward -- would eventually come as well. The second promise was given to assure them of the first.
"For God is not unjust to forget your work and labor of love which you have shown toward His name, in that you have ministered to the saints, and do minister. And we desire that each one of you show the same diligence to the full assurance of hope until the end, that you do not become sluggish, but imitate those who through faith and patience inherit the promises. For when God made a promise to Abraham, because He could swear by no one greater, He swore by Himself, saying, "Surely blessing I will bless you, and multiplying I will multiply you." And so, after he had patiently endured, he obtained the promise. For men indeed swear by the greater, and an oath for confirmation is for them an end of all dispute. Thus God, determining to show more abundantly to the heirs of promise the immutability of His counsel, confirmed it by an oath, that by two immutable things, in which it is impossible for God to lie, we might have strong consolation, who have fled for refuge to lay hold of the hope set before us. This hope we have as an anchor of the soul, both sure and steadfast" (Hebrews 6:10-19).
Consider: "Knowing this first: that scoffers will come in the last days, walking according to their own lusts, and saying, "Where is the promise of His coming? For since the fathers fell asleep, all things continue as they were from the beginning of creation"" (II Peter 3:3-4). In the future, in the last days, people will wonder what happened to Jesus promise to come. They will point out that those who received the promise have long since died and nothing has changed. Do you realize that this cannot match Preterism? According to the Preterists, Jesus said his coming would be within that current generation. There would have been no time for people to give up on his promise. And those who received the promise would not have all died by the fall of Jerusalem. The answer is that God doesn't view time as we do. But the delay is toward man's benefit. "The Lord is not slack concerning His promise, as some count slackness, but is longsuffering toward us, not willing that any should perish but that all should come to repentance" (II Peter 3:9). Peter's discussion makes perfect sense for us looking back 2,000 years to when the promise was given. It holds no meaning if, while writing in the late 60's, Peter was thinking about the destruction of Jerusalem in A.D. 70.