As Jesus was leaving Jerusalem and the Temple compound, he lamented over Jerusalem, wishing he could have protected her and her children, but the Jewish authorities, and because of them the nation, rejected him. Therefore, he declared that their House, i.e. their Temple would be left to them desolate (Matthew 23:37-38). That is, Jesus prophesied its destruction. Jesus’ disciples were astonished, and, while leaving with him, they pointed to the great stones comprising the Temple walls etc., no doubt wondering if they understood Jesus correctly. Did he really mean **these great stones** would be thrown down, leaving not two intact (Matthew 24:1)? Jesus merely repeated his statement in Matthew 24:2.
One can only imagine what the Apostles were thinking at this point, and when they arrived at the place where they would spend the night on Mount Olives, four of them, Peter, James, John and Andrew, came to him privately and asked:
And as he sat upon the mount of Olives, the disciples came unto him privately, saying, Tell us, when shall these things be? and what shall be the sign of thy coming, and of the end of the world? (Matthew 24:3; emphasis mine)
Both Mark13:4 and Luke 21:7 ask the same question as Matthew 24:3: “when shall these things be” but the only **sign** Mark and Luke ask is “when all these things shall be fulfilled (or come to pass),” so both of them lump together Matthew’s statements of Jesus’ coming and the end of the age (world). That is, according to Mark and Luke there is a single sign for both events.
Therefore, the disciples question “when shall these things be, and what shall be the sign of your coming, and the of end of the age” (or when all these things would be fulfilled) obviously shows they equated the destruction of the Temple with the end of the age. Clearly, the Olivet Discourse, therefore, could not be speaking of the end of our modern age, or the Christian age, or the end of time, etc. How could they have been thinking about an end of an age 2000 years into the future? How could they have been thinking of the Christian age, about which they knew nothing at all? And, why would they believe there would be an end to time? What in Jesus’ words in Matthew 23 would have prompted such a query?
Therefore, if Jesus answered the disciples question, which posited the destruction of the Temple, then the whole of his prophecy points to the fall of Jerusalem and the destruction of the Temple, and the throwing down of its great stones.
Jesus’ disciples equated the destruction of the Temple with the end of the age when God dealt with mankind through the Jewish nation. From Moses to Jesus, God dealt with the nations by working through the Jews. They were God’s people, who had God’s Laws and judgments etc. and they were supposed to be examples to the world. God had set their land between the two great empires of the ancient world, Egypt and Assyria/Babylon/Persia. God was known to the nations through the trade that transpired between the two empires, and through the wars they waged with one another. When Greece and the Rome conquered those lands, God was known to them through the Jews. Nevertheless, the Jewish nation became corrupt and misrepresented God to the world.
Therefore, the time had come when God would bring this age to an end, and he would do that by destroying the Jews’ capital city and their Temple and finally dispersing them among them nations. Destroying the Temple at Jerusalem ended the Old Covenant system of things. With the Temple gone, the Jews had to redefine their religious purpose, and that without a mandate from God. The end of the age cir. 70 AD left only the disciples of Jesus with a divine mandate to represent God to the world. It was this, when the Temple would be destroyed at the coming of Jesus into his Kingdom that the Apostles posited their question. A Kingdom without a physical, visible Temple would be a new age, indeed!