- (Premise) If p is overwhelmingly probable on the balance of God's evidence, then God believes p.
- (Premise) If open theism is true, then some of the propositions that are overwhelmingly probable on the balance of God's evidence are false.
- Therefore, if open theism is true, God believes some falsehoods.
- (Premise) God believes no falsehoods.
- Therefore, open theism is false.
What about (1)? This is tougher. It is false that rationality requires us to believe everything that is overwhelmingly likely. We have to be careful not to clutter our minds with junk beliefs, because our minds are limited. But this concern does not apply to God. But, maybe, we could say that God should be very careful to avoid false beliefs. However, it would be a sign of irrationality, of an undue punctiliousness, to withhold belief simply because there is some tiny non-zero probability of the belief being false. God is not irrational. So God will believe what is overwhelmingly likely.