Isaiah is done but Jeremiah looks to be just as tough to get through. I'm actually fondly remembering the wholesale slaughter in the Book of Joshua.
The guys sure aren't Elijah/Jesus level prophets.
How do we know Jeremiah is a prophet? He says he is.
How does HE know he's a prophet? God told him so. 'nuff said. After all, no one questions that John Smith was a true prophet.
So, we've proven Jeremiah is a prophet, but we don't get any profit out of the first few chapters in his book. Just the same old speech about Israelites turning away from God and God being sad.
Jeremiah doesn't mince words. He doesn't care much for the actions of Israel or Judah.
3:8 And I saw, when for all the causes whereby backsliding Israel committed adultery I had put her away, and given her a bill of divorce; yet her treacherous sister Judah feared not, but went and played the harlot also.
Even though they are both horrible states, God like Israel better. He gives them a chance.
3:12 Go and proclaim these words toward the north, and say, Return, thou backsliding Israel, saith the LORD; and I will not cause mine anger to fall upon you: for I am merciful, saith the LORD, and I will not keep anger for ever.
Finally, at the end of chapter 3 we get a little light prophecy about reunification, but any dime-store prophet could have prophesied that.