I think the single most instructive date that we should hang our Bible exposition on is the date that Jesus was crucified. I think the evidence is very strong that it was 31 AD. So much so that I cannot imagine any evidence coming forth at this point for another year.
I pick this date because that would mean that Jesus told the religious leaders they had committed the unforgivable sin in 30 AD, most likely on the 9th of Av, and that the sign that they would be judged by God was the sign of Jonah. Then 40 years to the day from that the temple was cast down in 70 AD.
Meanwhile true Pentecost was 8th of Av on 31 AD, and so the disciples began preaching to Jerusalem to repent for killing Jesus at that time giving them 39 years, (similar to Paul saying 40 lashes less one). During these 39 years the Jewish leaders suffered many things including the death of the high priest on day of atonement, the offering on Atonement never being accepted by God and being unable to shut the temple door.
Since 70 AD is confirmed and 31 AD fits perfectly with that as well as being considered the most likely year, it is very difficult to find a more solid nail to hang Bible exposition on.
The date of the siege of Jerusalem 586 BC is much better. Why?
Because God intentionally delineates that date to infallible perfection. Several times.
2Ki 25:1
And it came to pass in the ninth year of his reign, in the tenth month, in the tenth
day of the month,
that Nebuchadnezzar king of Babylon came, he, and all his host, against Jerusalem, and pitched against it; and they built forts against it round about.
Jer 39:1
In the ninth year of Zedekiah king of Judah, in the tenth month, came Nebuchadrezzar king of Babylon and all his army against Jerusalem, and they besieged it.
Jer 52:4
And it came to pass in the ninth year of his reign, in the tenth month, in the tenth
day of the month,
that Nebuchadrezzar king of Babylon came, he and all his army, against Jerusalem, and pitched against it, and built forts against it round about.
Eze 24:1
Again in the ninth year, in the tenth month, in the tenth
day of the month, the word of the LORD came unto me, saying,
Eze 24:2
Son of man, write thee the name of
the day, even of this same day: the king of Babylon set himself against Jerusalem
this same day.
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And appropriately, God delineated the EXACT DAY that He declares the 70 year captivity to be over.
Hag 2:10
In the four and twentieth
day of the ninth
month, in the second year of Darius, came the word of the LORD by Haggai the prophet, saying,
Hag 2:18
Consider now from this day and upward, from the four and twentieth day of the ninth
month, even from the day that the foundation of the LORD'S temple was laid, consider it.