I'm continuing my way through Joseph Blenkinsopp's A History of Prophecy in Israel, and I hope to finish it today or tomorrow.
In lectures and scholarly writings, I've often seen people contrast Jeremiah with Isaiah of Jerusalem. Jeremiah, on the one hand, predicted the destruction of Jerusalem for her sins, exhorting the Judahites not to believe that God would protect them, his city, and his beloved sanctuary. For many scholars, Isaiah had a different point of view, called the inviolability of Zion, which said that God would protect his city, no matter what. Consequently, Isaiah thought that the king of Judah didn't need to seek foreign assistance or take practical measures to safeguard Jerusalem (i.e., Hezekiah's water tunnel).
According to many scholars, Jeremiah was attacking the "inviolability of Jerusalem" concept that Isaiah held. And they like to wax eloquent on this. I recently read a scholar who repeated the mantra that Isaiah of Jerusalem would have been one of the "false prophets" whom Jeremiah was criticizing, had he lived in Jeremiah's time. Those trying to get a theology out of the Bible's tensions usually say that God has different messages for various times and contexts: for Isaiah's day, God supported the "inviolability of Zion"; for Jeremiah's day, God planned to destroy Jerusalem for her sins.
I've long had problems with this spiel, especially the way that scholars act like they're so brilliant whenever they parrot it. That's why I was happy to read pp. 108-109 of Blenkinsopp: he saw more nuance in the situation. Blenkinsopp states that "The Zion theology of the book [of Isaiah]...differs...in some basic respects from the official 'state church' ideology." Blenkinsopp goes on to say in a later paragraph:
Isaiah himself does not hesitate to compare this real Jerusalem with Sodom (1:10), denounce it as a harlot city (1:21), and hold out the prospect of ruin and destruction (8:5-8, etc.). Only in one saying, probably from the time of Hezekiah's rebellion (31:4-5), does he speak of Yahweh fighting for and protecting his city, though even in this instance there are conflicting interpretations.
That was my impression when I read the Book of Isaiah roughly a decade ago. Isaiah talks about God protecting Jerusalem, but he's not an advocate of cheap grace, for he affirms that God will punish sin. In Isaiah 4, the prophet says that God will bring the city down and rebuild it with its few survivors. That differs slightly from Jeremiah's view that God will utterly destroy the city, but it's also a far cry from the "peace and safety" message that the false prophets of Jeremiah's day were proclaiming.
Overall, I agree with the theologians who say that God varies his message according to the context, but I'd base that view on something other than "Isaiah and Jeremiah differed because the political contexts of their times were different." When Isaiah was alive, Micah had the same message as Jeremiah---that Jerusalem would be destroyed for her sins (Jeremiah 26:18-19). So much for the spiel of "the inviolability of Zion was God's message for Isaiah's day, and the destruction of Jerusalem was God's message for Jeremiah's time."
I think that Jeremiah 26:19 is crucial in this discussion: King Hezekiah repented, so God changed his mind about destroying Jerusalem. Isaiah has different messages in his book because the spiritual condition of Judah was in flux.
Moreover, although Jeremiah predicted the destruction of Jerusalem, he also carried a message that God would protect his people. After the Babylonians destroyed Jerusalem, they appointed Gedaliah to be over Judah. A group of Judahites killed him in an attempt to restore the Davidic reign, and many in Judah were afraid that the Babylonians would harshly retaliate. In Jeremiah 41, however, the prophet exhorts them not to fear the king of Babylon, for God will protect them. Previously, Jeremiah said that God wouldn't protect his city. Now, Jeremiah preaches protection. Why? Because the situation is different.