Does God not exactly know what we are going to do?

Answer:

Not exactly. God knows us better than we know ourselves. He can and does predict what we will choose to do in most things. But some things are not predictable. Remember when God sent Jonah to prophesy that Nineveh would be destroyed in 40 days? The people all turned to God and God changed His plan.

"The instant I speak concerning a nation and concerning a kingdom, to pluck up, to pull down, and to destroy it, if that nation against whom I have spoken turns from its evil, I will relent of the disaster that I thought to bring upon it. And the instant I speak concerning a nation and concerning a kingdom, to build and to plant it, if it does evil in My sight so that it does not obey My voice, then I will relent concerning the good with which I said I would benefit it" (Jeremiah 18:7-10).