No nation lasts forever. Therefore the prediction that a nation will fall is not particularly impressive. Someday America will fall. That prediction does not make me a prophet.
No earthly one has.
Since you seem intent on discussing prophecy to the exclusion of all else however let's assume for a moment that some biblical prophecy is true and impressive. It still doesn't tell us where this prophecy originates only that predictions were made. Even if the prophets claim a source how can we ever demonstrate that the source they claim is the actual source of the prophecy? It could have been from some god(s) or it could have been some devil(s) or it could have been beamed into their mind by space aliens or they could be the source themselves without the need for an external agency. Even if biblical prophecy were impressive as prophecy
it is still unimpressive as evidence of any god(s).
I discuss prophecy because the unbeliever keeps insisting there is no proof that the Bible is reliable or accurate in what it says. Once I establish that it is in this area it leaves the question open as to it being so in other areas. And who do you know who can predict things before they happen with 100% accuracy? God would be able to do this.
When you say, "let us assume...that some biblical prophecy is true and impressive" - it is. Daniel 9:24-27 predicts the fall of the city and temple ONE other time. We know that happened in AD 70. The timeframe was given, 490 years from the issuing of the decree, plus the killing of the Anointed One and the six specific conditions to take place gives a specific timeframe of when this will happen.
You suggest some other means could be possible, yet this reads into Scripture things it does not say. It is pure speculation. What we are given information of in the writings comes to pass. We are told that God gives Daniel visions of what will happen to HIS people in the far-off future. The same for other prophets. That claim a revelation from God and a warning of judgment to these Mosaic Covenant people for breaking the covenant. That warning will result in the curses of Deuteronomy 28 if they do not repent. They do not.
Exodus 24:3 (NASB)
3 Then Moses came and recounted to the people all the words of the Lord and all the [a]ordinances; and all the people answered with one voice and said, “All the words which the Lord has spoken we will do!”
Deuteronomy 28:15 (NASB)
Consequences of Disobedience
15 “But it shall come about, if you do not obey the Lord your God, to observe to do all His commandments and His statutes with which I charge you today, that all these curses will come upon you and overtake you:
Then Deuteronomy 28 lists the curses, these same curses we witness in the fall of Jerusalem in AD 70.
The Olivet Discourse gives very precise predictions about what will happen to Jesus' disciples and Israel after He leaves them and before He returns. The return will result in the judgment of the living and the dead. It will be a time for Israel like no other it has ever experienced for at that time God will divorce Israel as His people and take a new bride, a faithful one.
Matthew 24:3 (NASB)
3 As He was sitting on the Mount of Olives, the disciples came to Him privately, saying, “Tell us, when will these things happen, and what will be the sign of Your coming, and of the end of the age?”
Jesus then goes on to tell His disciples what will happen and the pronoun 'you' that follows signifies what will happen and when these things will happen when He will come again, and when the age they live in will end. After His death Acts records many of these things happening, where they are persecuted, come before kings, and are killed because of Him.
Not one NT writing tells of an already destroyed temple or city, yet everywhere in the NT we see warnings of NEAR, SOON, QUICK, AT HAND, judgment. It is all about to happen. AD 70 is the end of the Mosaic age. There is no longer a temple to bring what is necessary to fulfill the Law of Moses, an animal sacrifice offered on their behalf. There is no longer a priesthood to act as a mediator between the people and God. There is no longer feast days and the ritual system of worship as prescribed by the Mosaic Covenant, for these feast days required specific animal sacrifices. None of this can be fulfilled after AD 70. What these people had known for fifteen hundred years, this special relationship with God is no longer possible as prescribed. It is taken out of the way because of their disobedience. God continually sent prophets to warn those people to turn back from idols. They never listened. Then He sent His Son. They rejected Him, so God in His mercy gave them 40 years to repent and then the judgment.
(Hebrews 3:6-19 to 4:1-11)
7 Therefore, just as the Holy Spirit says,
“Today if you hear His voice,
8 Do not harden your hearts as when they provoked Me,
As in the day of trial in the wilderness,
9 Where your fathers tried Me by testing Me,
And saw My works for forty years.
10 “Therefore I was angry with this generation,
And said, ‘They always go astray in their heart,
And they did not know My ways’;
11 As I swore in My wrath,
‘They shall not enter My rest.’”