OK! So atheists can't be angry at God because they don't believe in God. Or can they?
Perhaps the answer is no. Lee Strobel was angry with God, but not an atheist. But, that would mean the same for all "atheists" who are angry at God. I suspect that there are a lot of such "atheists," even on this forum. Jea and Jeff spring to mind.
Or, it could be an example of compartmentalization. Atheism is an intellectual position that God does not exist. Anger is an emotional response. So, anger does not mean actually intellectually acknowledging God to exist.
Or, perhaps, Lee Strobel may have just been someone who thought, "I want to disbelieve."
Either of these scenarios could be true, and Lee Strobel could have been sincere in his desire to debunk Christianity.