I'm not sure if anyone has read "God's Debris: A Thought Experiment", by Scott Adams (the author of the Dilbert cartoons). In it, one of the characters (it's a fictional book) makes the claim that even though most people claim to believe in God, deep down they really do not. He claims that they don't act the way someone should (or would have to) act if they truly believed in the existence of an all-powerful, supernatural being. If the belief was true deep-down to their core, then their lives should be much more focused on fulfilling the wishes of God and trying to live their lives in accordance. His claim is people say they believe because they enjoy the practical benefits of doing so (comfort, emotional support, etc.). He uses the analogy of believing in a truck that is speeding towards you. Saying you believe in the truck is one thing, but if it truly does not scare you to the point of getting out of the way, then you don't really believe in what it is and what it could do to you.
I think this would be an interesting topic to discuss. Note that I don't want to discuss whether God actually exists or not, but rather the question of whether everyone that claims to believe in God *truly believes*. I'm sure a small percentage of them actually do, with everything that encompasses. But perhaps others only believe symbolically, while others may believe in an actual God but one that differs from the traditional view. The second part of this would be to analyze why this phenomenon occurs in the first place.