Revelation was written before the destruction of that temple in Jerusalem, before A.D. 70.
There are very many evidences within the scriptures that are time texts and indicators for that generation in which Christ was made manifest on earth. The Bible is the Holy Spirit's record who provided us with God's word, and should be our first and final authority / source for all things pertaining to God. (sola scriptura)
Many people insist that all of the Bible is to be taken literally, yet they seem to twist the meanings of very explicit and plain words into nonsense, and then proceed to make the symbolic and metaphorical prophetic language into absolute literals. They have turned the literal statements inside out, and upside down.
Surely we can all agree that Christ was manifested on earth in the first century AD. He came in the fullness of time (Mark 1:15; Gal. 4:4). Therefore, the time was important, and the time in which Christ spoke and of which He promised is important.
Christ came preaching that the kingdom was "at hand". Let's explore some of the time statements in the Bible.
Gen. 27:4, when Esau knew Jacob had received the blessing of the first born,
"And Esau hated Jacob because of the blessing wherewith his father blessed him: and Esau said in his heart, The days of mourning for my father are at hand; then will I slay my brother Jacob." (KJV)
It is clear that "at hand" in the above verse meant the present days with Esau. The sense doesn't even allow for a week or a month later. The days of Esau's mourning were those days immediately following the death of his father, Isaac.
Matt. 26:45, Jesus said just within hours of his betrayal,
"Then cometh he to his disciples, and saith unto them, Sleep on now, and take your rest: behold, the hour is at hand, and the Son of man is betrayed into the hands of sinners." (KJV)
"And the Jews' passover was at hand, and Jesus went up to Jerusalem." (KJV)
2 Tim. 4:6, Paul speaking of his soon death,
"For I am now ready to be offered, and the time of my departure is at hand." (KJV)
The sense of these verses is clearly of a time that was either instantly present, or within hours, or days of happening. Then, when Christ said that the kingdom was "at hand" in the first century A.D., we can know that "at hand" meant soon. It was nearly there when He spoke those words in 28 - 30 AD.
The meaning of "at hand" cannot be stretched across 2,000 + years.
Since Christ came to them in the fullness of time, and since He told them the Kingdom was "at hand", then the kingdom was associated with His manifestation on earth in the first century A.D.
" And Abraham hastened into the tent unto Sarah, and said, Make ready quickly three measures of fine meal, knead it, and make cakes upon the hearth." (KJV)
The word "quickly" meant hurry, or do it as fast as you can.
Gen. 27:20, Isaac speaking to Jacob,
"And Isaac said unto his son, How is it that thou hast found it so quickly, my son? And he said, Because the LORD thy God brought it to me." (KJV)
"And the ambush arose quickly out of their place, and they ran as soon as he had stretched out his hand: and they entered into the city, and took it, and hasted and set the city on fire." (KJV)
Matt.28:7, of Jesus' resurrection,
"And go quickly, and tell his disciples that he is risen from the dead; and, behold, he goeth before you into Galilee; there shall ye see him: lo, I have told you." (KJV)
"And they went out quickly, and fled from the sepulchre; for they trembled and were amazed: neither said they any thing to any man; for they were afraid." (KJV)
John 13:7, Jesus speaking to Judas,
"And after the sop Satan entered into him. Then said Jesus unto him, That thou doest, do quickly." (KJV)
"Quickly" as used in the NT had the same sense of urgency as when used in the OT. They were to hurry.
Gen 12:11, Abraham speaking to Sarai,
"And it came to pass, when he was come near to enter into Egypt, that he said unto Sarai his wife, Behold now, I know that thou art a fair woman to look upon:"
The word "near" meant about to happen, close to, or ready.
1 Sam. 4:19,
"And his daughter in law, Phinehas' wife, was with child, near to be delivered:..." (KJV)
"Now in the twelfth month, that is, the month Adar, on the thirteenth day of the same, when the king's commandment and his decree drew near to be put in execution, in the day that the enemies of the Jews hoped to have power over them,..." (KJV)
And, in the NT, Luke 15:1,
"Then drew near unto him all the publicans and sinners for to hear him." (KJV)
Luke 19:41, Jesus looking upon Jerusalem,
"And when he was come near, he beheld the city, and wept over it," (KJV)
Acts 9:3, of Paul on the road to Damascus,
"And as he journeyed, he came near Damascus: and suddenly there shined round about him a light from heaven:" (KJV)
The meaning did not change from the OT to the NT. "Near" still meant close.
So, when Christ said in Matt. 24:33,
"So likewise ye, when ye shall see all these things, know that it is near, even at the doors." (KJV)
He didn't mean thousands of years later. The prophesy of the end in Matthew c. 24 was close to them in that century in which He spoke the words.
Gen 41:32, Joseph explained Pharaoh's dream of the famine,
"And for that the dream was doubled unto Pharaoh twice; it is because the thing is established by God, and God will shortly bring it to pass." (KJV)
The word "shortly" meant the time was close, or near, or soon.
Ezek. 7:8, speaking of Babylon's destruction of Judah and Jerusalem,
"Now will I shortly pour out my fury upon thee, and accomplish mine anger upon thee: and I will judge thee according to thy ways, and will recompense thee for all thine abominations." (KJV)
This prophesy came upon Jerusalem about three (3) years after it was spoken.
"But Festus answered, that Paul should be kept at Caesarea, and that he himself would depart shortly thither." (KJV)
"But I trust in the Lord Jesus to send Timotheus shortly unto you, that I also may be of good comfort, when I know your state." (KJV)
2 Pet. 1:14, speaking of his near death,
"Knowing that shortly I must put off this my tabernacle, even as our Lord Jesus Christ hath shewed me." (KJV)
The meaning of the word "shortly" as used in the NT did not change from its use in the OT. It still meant "soon" or "near" or "close", within hours, or days, or very few years.
So, when Holy Spirit said in Rev. 1:1,
"The Revelation of Jesus Christ, which God gave unto him, to shew unto his servants things which must shortly come to pass; and he sent and signified it by his angel unto his servant John:"
the word "shortly" still had the same meaning of soon, or close, or within just a few years.
"Blessed is he that readeth, and they that hear the words of this prophecy, and keep those things which are written therein: for the time is at hand."
"And he saith unto me, Seal not the sayings of the prophecy of this book: for the time is at hand."
Rev. 3:11, Christ to the church at Philadelphia,
"Behold, I come quickly: hold that fast which thou hast, that no man take thy crown."
"Behold, I come quickly: blessed is he that keepeth the sayings of the prophecy of this book."
"And he saith unto me, Seal not the sayings of the prophecy of this book: for the time is at hand."
"And, behold, I come quickly; and my reward is with me, to give every man according as his work shall be."
"He which testifieth these things saith, Surely I come quickly. Amen. Even so, come, Lord Jesus."
Christ was most emphatic that all of the things prophesied in Revelation from the first chapter to the last chapter was close to them when the words were given to John. They were not going to be stretched out in time. They certainly were not prophesied for 2,000 or more years into the future.
In Heb 10: "For yet a little while, and he that shall come will come, and will not tarry.". The Hebrew for 'little while' is actually 'very very little' and yet people have twisted the clear meaning and have been teaching that our Lord has not come for the last 2000 years.
As the prophesy of Matthew c. 24 was about the end of that temple in Jerusalem which occurred in A.D. 70; and since Christ came preaching and promising that the kingdom was "at hand" in the first century AD (Matt. 4:17); and since Christ told them that the men of Nineveh would rise up in judgment of that generation (Luke 11:32); and since Christ told them that all the righteous blood shed from Abel to Zacharias was going to fall upon them (Matt. 23:35); and, since Christ told them that all of the blood of the prophets shed from the foundation of the world was going to be required of that generation (Luke 11:50) - then we can know for a certainty that the judgment was to come upon that generation in which He was manifested on earth, and in which He spoke those words.
And, as Christ told His disciples that they would not finish going through the cities of Israel before He came (Matt. 10:23); and as Christ told His disciples that John would live to see His coming (John 21:22-23); and as Christ told His disciples that their generation would not pass till all of those things were fulfilled (Matt. 24:34); and since Christ told the disciples that their days were the days of vengeance (John 21:22) - then we can know assuredly that He literally meant He was coming back to them in their generation, in their lifetime.
Revelation was about His return, about His second appearance as promised to them of the first century A.D. (Heb 9:28).
"Behold, he cometh with clouds; and every eye shall see him, and they also which pierced him: and all kindreds of the earth shall wail because of him. Even so, Amen."
Those who pierced Him lived in the first century A.D. They could not see His "second" coming if they are already dead.
Therefore, the scriptures literally prove that His second "coming" was accomplished in the lifetimes of those who heard Him speak, of those who touched Him, and witnessed His death on the cross (1 John 1:1-3) in the first century A.D.
The current teachers of future "end times" eschatology claim that they are "interpreting" the Bible literally, but they then twist the clear meanings of the time statements in the scriptures in order to accommodate a biased point of view that suits their learned and taught perceptions of traditions of men.
They skew the clear time statements into future years, and future generations which were never taught by Christ or the apostles. But, their desire to stretch the meanings of the words "near", "soon", and "shortly" into thousands of years presents our Lord and Savior as a liar and deceiver to all of the world.
If Christ didn't say exactly what He meant, then why should anyone believe Him? And, as they are constantly saying they must "interpret" the scriptures literally, then why are they not taking the literal meaning of these time statements?
Revelation was written before the destruction of Jerusalem and that temple, most probably in AD. 66 - 68 within a very short time of A.D. 70. As that temple was the center of the Jewish life, if Revelation had been written after its destruction it could not have failed to have been mentioned in the book.
Persecution from the Sanhedrin before A.D.70
Jews were present throughout Asia in the Roman provinces, and their synagogues were under control of the Sanhedrin in Jerusalem for all matters including collection of the temple tax. A decree by Julius Caesar issued in 47 BC reinforced the practice originally allowed under the Hasmoneans for the Sanhedrin to police their own. The high priest had complete sovereignty over all matters of their Jewish religion.
This religio licita was a privilege for the traditions and religions of the peoples of the Roman provinces as long as they were not offensive to Roman laws or gods. That Paul requested and received letters to arrest or extradite any man or woman in Damascus that had converted to The Way (Acts 9:1-2) in order to bring them back to Jerusalem for trial indicated this was an established practice.
So, the Sanhedrin regulated the synagogues of the diaspora cities throughout the Roman empire, and was operating under Roman law to persecute any Jew that converted to Christianity. They held this right of "extradition" privileges over any synagogue in any of the Roman provinces until the destruction of Jerusalem in A.D. 70. See: here.
After AD 70 the Sanhedrin no longer held that sovereignty or authority in any province of Rome. Therefore Rev. 2:9 and 3:9 referring to those who say they were Jews of the synagogue of Satan would not have been of such import if the book had been written after A.D. 70.
Other external evidences you may like to explore are:
Robert Young's Analytical Concordance on Revelation,
"It was written in Patmos about A.D. 68, whither John had been banished by Domitius Nero, as stated in the title of the Syria version of the book; and with this concurs the express statement of Irenaeus in A.D. 175, who says it happened in the reign of Domitianou – i.e., Domitius (Nero). Sulpicius, Orosius, etc., stupidly mistaking Domitianou for Domitianikos, supposed Irenaeus to refer to Domitian, A.D. 95, and most succeeding writers have fallen into the same blunder. The internal testimony is wholly in favor of the early date.”
J.A.T. Robinson (1976) from Redating the New Testament, p. 13:
“One of the oddest facts about the New Testament is that what on any showing would appear to be the single most datable and climactic event of the period — the fall of Jerusalem in A.D. 70 — is never once mentioned as a past fact. . . . [T]he silence is nevertheless as significant as the silence for Sherlock Holmes of the dog that did not bark”.
There just is not space here to provide all of the abundant proofs that exist for the early date of Revelation. I have presented many more scriptural evidences for the "second" appearance of Christ and for the date of the book of Revelation in that same century in which Christ was manifested on earth at my blog [ShreddingTheVeil]. ["It's Not the End of The World, Part V - Dating the Book of Revelation"], and ["The Signs of Revelation, Part I - The Time of His Coming"] provide many references to consider.