19 But now they have returned to their God, and they have come back from the Diaspora where they were scattered. They have reclaimed Jerusalem, where their sanctuary is, and have settled again in the hill country, because it was unoccupied.
20 “So now, my master and lord, if these people are inadvertently at fault, or if they are sinning against their God, and if we verify this offense of theirs, then we will be able to go up and conquer them. 21 But if they are not a guilty nation, then let my lord keep his distance; otherwise their Lord and God will shield them, and we will be mocked in the eyes of all the earth.”
Here we see this idea that "it has been proven" that when the Jews follow their God, then they are unstoppable, but when they sin against their God their own God will destroy them. So, anyone going against the Jews needs to understand if they are on the right side or wrong side of their own god. So where is this established? Look at works like Jeremiah.
We can take all of Jeremiah, which opens with prophecies against Israel. But following the destruction and punishment of Israel, we are then told of the prophecies against the Nations: Egypt, the Philistines, Moab, Babylon, etc.
Who is the audience here? It isn't Babylonians, nor is it ancient Israelites. The audience here are the Greeks, and others who would plan to conquer and subjugate the Jewish people. The message. "Our God is all-powerful, he will destroy any and all who oppress us. Look at the examples of the past. Don't be a fool. Even if you think you have won, our God will not forget and he will take vengeance on you. Look at all of the great civilizations who tried to enslave us? All were punished by our God."
Is this some historical account of the Babylonian conquest? Hell no. Does the writer actually know anything about the Temple? No. This is a Hellenistic story about the resilience of the Jewish people and the power of their God, who is so friggen hard-core that he will smite his own people and destroy his own house, but just like a father who beats his own kids, he'll beat you even worse.