"For the Son of Man is going to come in the glory of His Father with His angels, and WILL THEN REPAY EVERY MAN ACCORDING TO HIS DEEDS. Truly I say to you, there are some of those who are standing here who will not taste death until they see the Son of Man coming in His kingdom." Matthew 16:27-28
They also said, "Men of Galilee, why do you stand looking into the sky? This Jesus, who has been taken up from you into heaven, will come in just the same way as you have watched Him go into heaven." Acts 1:11
BEHOLD, HE IS COMING WITH THE CLOUDS, and every eye will see Him, even those who pierced Him; and all the tribes of the earth will mourn over Him. So it is to be. Amen. Revelation 1:7
Reading Revelation 1:7, it is understandable why we want to assign an early date to the writing of John. After all, it says that "even those who pierced Him" would see Him, and how could this be if they are already dead? Apparently there were some kind of angelic appearances in the sky in A.D. 66, which many attribute to the coming of the Lord. While this may have been a fulfillment of some kind, or at least a sign of some kind, it still remains extremely problematic.
First, Irenaeus, the disciple of Polycarp who was the disciple of the apostle John, vies for a later date.
Second, the internal text says that John was on the Isle of Patmos at the time of his writing. External evidence says he was exiled there during the reign of Domitian, which was well after A.D 70. Clement of Alexandria says he returned from Patmos after the death of Domitian.
Third, when Paul wrote to the Ephesians in A.D. 61-63, he commended them for their love. It is doubtful to believe that in just 3 years Jesus would be admonishing them for having left their first love. Not to mention, if Timothy was in Ephesus looking after the church there, after Paul had founded the church in Ephesus, when did the apostle John look after them?
Many good arguments can be raised based on how certain individual verses are written, but we cannot isolate certain verses at the expense of others. We need to pay attention to everything. When Jesus predicted the destruction of the temple, His disciples had asked Him two questions. The answer to the first was fulfilled in A.D. 70. There was likely a sign in connection with this, such as the angelic appearances in A.D. 66, but the Second Coming of Jesus did not occur. Even the text of Matthew 16:27-28 opposes this belief. Was "every man" repaid "according to his deeds"? Were every man's works tested and judged? Did the separation of goats and sheep happen? No! Of course not. The resurrection of all men, some to eternal destruction and some to eternal life, never happened on this date. The judgment of all men never happened on this date. The destruction of sin and the defeat of death never happened on this date.
The Bible makes it clear that when Jesus returns, sin and death will be defeated, all mankind will be judged, and eternity will be ushered in. Men will no longer be able to sin. Death will no longer reign. There will be no need for faith and hope. All of these are things that still persist today. So clearly Jesus could not have returned already. Not to mention that Acts 1:11 says He will return exactly as He left. It does not say He will merely return in the clouds. Again, if He merely returned in the clouds without stepping down on Earth, and all true believers were "raptured" to Him at this time, that means the Holy Spirit would have been removed and there would be no way for anyone post A.D. 66 to be preached to and come to a knowledge of the Saviour. That means that there should be records of mass groups of people suddenly vanishing, or, better yet, being witnessed of being received into the sky. This kind of event would definitely make the news.
Also, if Revelation was written earlier than A.D. 70, because there is no mention of the destruction of Jesusalem, then the Gospel of John would have to be written later than A.D. 70 for the same reason. Do you really believe that if Revelation were written prior to A.D. 70, with the destruction of Jerusalem on John's mind, that he would not have written in his Gospel to warn people to flee the pending destruction, which was only about 4 years away? Either way, the full Preterist view fails because there are books of the Bible written after A.D. 70 and there are events fulfilled after A.D. 70.
Emperor Nero is not the "Anti-Christ." This calculation fails on numerous accounts. First, you have to use Hebrew in order to calculate it. Second, you have to add his title—"Caesar"—to his name in order for it to work. Third, you have to drop one of the Hebrew letters in order for the calculation to work out correctly. Fourth, you have to use Latin in order to calculate the variant of 616. The book was written in Greek. It calls Jesus the Alpha and Omega, which are the first and last letters of the Greek alphabet. In order to calculate the name, you have to use Greek—not Hebrew and not Latin. Titus is a much better fit for the "Anti-Christ" as his name—in Greek—amounts to 666, as does the word "Lateinos" (Λατεινος) and the phrase "the Latin Empire" (η Λατινη Βασιλεια).
By the way, under Nero, Peter and Paul were murdered. If the book of Revelation were written during the time of Nero, why would Nero merely exile John? It is extremely inconsistent with his practices. But it is entirely consistent with Domitian's tortures.