I need some help understanding God's actions in the books of Jesaja and Jeremiah.
So the main element of the story is that God is planning to punish Israel for their sins. Many times through his prophets he says things such as: "Babylon is my servant, my sword, the tool I will use to punish Israel. I will use them to unleash my wrath upon Israel". I can't be bothered to look for the actual quotes, but if you are familiar with the books you certainly know what I mean.
But when all is said and done, God then basically says: "Okay, I've punished them enough and I forgive them. All is fine, you can come home now. But the people of Babylon, who enslaved you and treated you badly, I will purge from the face of the earth for the sins they did to my chosen people".
So, basically, "Hey, Babylon, go do some dirty work for me about Israel because I'm annoyed of them. Thanks, Babylon. Now I shall punish the living hell out of you for doing what I told you to do".
How is this okay?