No it's not a joke. Basically I was just in Hollywood and these incredibly devout Christians were spouting their usual bullshit, taking questions, and answering them by saying "You must except God, blah blah blah." So I was wondering what is a good logical question that I can ask someone like this the next time I see them?

This issue has been addressed many times before.

Quick answer is, you can't stump a true believer. You can annoy them maybe, but it isn't prudent or productive.