If God knows every detail of the future with infallible certainty, then (by definition) the outcome of all things is already determined. And if things are predetermined but God did not ordain whatsoever comes to pass, then you have two choices:
1. A higher sovereignty belongs to some being (or beings) other than God. That is idolatry.
2. Some impersonal force did the determining. That is fatalism.
Therefore if the thinking Arminian wants to avoid both fatalism and idolatry, he or she must deny God’s foreknowledge, thereby nullifying God’s omnscience—in other words, they essentially undeify God. That is of course blasphemy. But that is precisely the road Open Theism takes.
by Phil Johnson