This is another in a series of questions, criticisms, and attacks posed by skeptics.
Question: How can God know His future decisions? If God is all-knowing, how can He make any decisions at all, or choose one thing over another? If He were all-knowing, He would not be able to make a future decision, for He would already know everything. He would not even be able to think.
Response: Perhaps criticisms like this are the root of the claim that atheists do not understand God. Nevertheless, the question is confused and has a rather straightforward answer.
Here, the skeptic is half correct. Since God is all-knowing, it is correct that He does not make future decisions. Further, since time is a measure of change, and God does not change, He is timeless and does not experience before and after as we do. Thus when God acts, He acts from timeless eternity in one unified act. This unified act of God results in many sequenced effects that we experience as present and future.
A simple analogy can illustrate. A doctor can give a single prescription to give medicine three times per day for a week. The one order from the doctor results in many future effects that happen in sequence. There is no logical contradiction in a timeless, changeless God acting from a timeless eternity, yet multiple effects happening in seqence in a changing world.