I have a buddy at work that was taking a philosophy of Religion class in college. We would debate the classical arguments for the existence of God all the time e.g. cosmological, ontological.... Every now and then a different guy at work, usually one of the younger Mormon kids that haven't done much independent thinking on the subject, would chime in with a response based upon their religious teachings such as the existence of the bible as proof of God's existence. To which I would have to say to them that their arguments are practically invalid because they already presuppose that God exists.
This to me is the same thing that bugs you about "Pop" atheists, only coming from the other end of the spectrum. It is just as weak to claim to be an atheist without any philosophical grounding as it is to claim to be a theist without any philosophical grounding.