Can God make a rock so big that he can't lift it?
A Christian who was genuinely confused sent me an email with that question a while ago, and I was happy to try my best to respond.
But I suspect that most people who ask this question do it to show Christians that there is something their God cannot do. So nya, nya, nya! But frankly, methinks the critics exert themselves overly much. After all, they could just look at Hebrews 6:18, which says it is impossible for God to lie. There! Something God cannot do. Satisfied?
No, they'd rather ask one of those silly damned-if-you-do, damned-if-you-don't questions, like, "Do you still beat your wife?" (I do, but only at foosball.)
So, for what little it's worth, let me try to answer the question.
God, by definition, is greater than anything else, so if God created a rock so heavy that he couldn't lift it, then he'd stop being God, because the rock would then be greater than him.