Why God doesn't stop satan?

[Angrboda]

If it was possibly true, then it's possibly true that P3 will be false (at that point). 

This doesn't follow. God knows the outcome of D's free will, as a result of his omniscience.

Also, P1 is necessarily true, but it states an outcome of free will. One can't choose other than what they already chose (duh.)

If it's possibly true that P1 will be false, then it doesn't follow that P3 is possibly false? That's basic logic, Klor, of course it follows. I realize you don't like it, but it definitely follows.

P1, by stipulating that her choice is free logically entails that at some point the truth of P1 was in doubt. If the truth of P1 is in doubt, the truth of P3 is in doubt.

That violates God's omniscience.

P1 can only be the result of free will if it is contingently true. If it's necessarily true, then it wasn't a result of free will. Think about it. If its necessarily true that the sun will rise in the east, it's not a free event.