All the gospels were written down anonymously AFTER the destruction of Jerusalem. Try again. I mean, seriously, name ONE prophecy in the Bible that has come true where we can prove the prophecy was written BEFORE the event. Just one.
Okay, Isaiah 52-53:
The Lord hath made bare his holy arm in the eyes of all the nations; and all the ends of the earth shall see the salvation of our God. … Behold, my servant shall deal prudently, he shall be exalted and extolled, and be very high. As many were astonied at thee; his visage was so marred more than any man, and his form more than the sons of men: So shall he sprinkle many nations; the kings shall shut their mouths at him: for that which had not been told them shall they see; and that which they had not heard shall they consider.
Who hath believed our report? and to whom is the arm of the Lord revealed? For he shall grow up before him as a tender plant, and as a root out of a dry ground: he hath no form nor comeliness; and when we shall see him, there is no beauty that we should desire him. He is despised and rejected of men; a man of sorrows, and acquainted with grief: and we hid as it were our faces from him; he was despised, and we esteemed him not. Surely he hath borne our griefs, and carried our sorrows: yet we did esteem him stricken, smitten of God, and afflicted. But he was wounded for our transgressions, he was bruised for our iniquities: the chastisement of our peace was upon him; and with his stripes we are healed.
All we like sheep have gone astray; we have turned every one to his own way; and the Lord hath laid on him the iniquity of us all. He was oppressed, and he was afflicted, yet he opened not his mouth: he is brought as a lamb to the slaughter, and as a sheep before her shearers is dumb, so he openeth not his mouth. He was taken from prison and from judgment: and who shall declare his generation? for he was cut off out of the land of the living: for the transgression of my people was he stricken.
And he made his grave with the wicked, and with the rich in his death; because he had done no violence, neither was any deceit in his mouth. Yet it pleased the Lord to bruise him; he hath put him to grief: when thou shalt make his soul an offering for sin, he shall see his seed, he shall prolong his days, and the pleasure of the Lord shall prosper in his hand. He shall see of the travail of his soul, and shall be satisfied: by his knowledge shall my righteous servant justify many; for he shall bear their iniquities. Therefore will I divide him a portion with the great, and he shall divide the spoil with the strong; because he hath poured out his soul unto death: and he was numbered with the transgressors; and he bare the sin of many, and made intercession for the transgressors.
Every single element of this prophecy was fulfilled in the gospels of Jesus Christ. Not only was Jesus rejected by his people, he paid for their transgressions as an offering for sin. He “made his grave with the wicked” in that he died between the two thieves; and “with the rich in his death,” being buried in the tomb of a wealthy man.
For a more modern prophecy: Isaiah 11:11-12
And it shall come to pass in that day, that the Lord shall set his hand again the second time to recover the remnant of his people, which shall be left, from Assyria, and from Egypt, and from Pathros, and from Cush, and from Elam, and from Shinar, and from Ha math, and from the islands of the sea. And he shall set up an ensign for the nations, and shall assemble the outcasts of Israel, and gather together the dispersed of Judah from the four corners of the earth.
The first time the Jews were gathered to Jerusalem was in the days of the Babylonian conquest. But there was no “second time” that they were recovered except in 1947, when Israel was established as a nation. Since the mid-1800s, Judah has been gathered to its ancestral homelands. Zechariah said that in the last days Jerusalem would be a “burdensome stone” for all nations. In fact, he wrote: “Behold, I will make Jerusalem a cup of trembling unto all the people round about, when they shall be in the siege both against Judah and against Jerusalem. And in that day will I make Jerusalem a burdensome stone for all people: all that burden themselves with it shall be cut in pieces, though all the people of the earth be gathered together against it.
During the battle of Armageddon, this will be more profoundly appreciated. Even so, this is the first time in history when the people “round about” Jerusalem would be gathered against it. This happened in 1948 and in 1968, and both times Israel creamed those nations when many thought it would be destroyed. The Lord prophesies:
“And it shall come to pass in that day, that I will seek to destroy all the nations that come against Jerusalem. And I will pour upon the house of David, and upon the inhabitants of Jerusalem, the spirit of grace and of supplications: and they shall look upon me whom they have pierced, and they shall mourn for him, as one mourneth for his only son, and shall be in bitterness for him, as one that is in bitterness for his firstborn. In that day shall there be a great mourning in Jerusalem, as the mourning of Hadadrimmon in the valley of Megiddon.”
Even though this is an Old Testament writing, the reference to the nations “round about” Jerusalem being Israel’s mortal enemies and that they would ultimately gather in the valley of Armageddon. Also, that they shall “look upon me whom they have pierced.” This is a clear messianic reference to Jesus being “pierced” as well as those referring to the “only son” and the “firstborn.”
These are all self-evident prophecies written well before their fulfillment. There are many other prophecies relating to the future that are equally intriging. As for the Christians fleeing to Pella, it's well documented. You can find it on the Internet. Add to that all the traditions of Christians surviving the Jerusalem assault.