I get the sense you aren't interested in this sort of feedback, but I'll give it a shot just in case: I think when the average Christian or Muslim claims that

I get the sense you aren't interested in this sort of feedback, but I'll give it a shot just in case: I think when the average Christian or Muslim claims that God is omnipotent, they mean something like "God can do all logically possible things that don't fundamentally contradict its character." Why's that matter? Because the proof by contradiction you've constructed doesn't apply in their frame of reference.