Nathan Phelps (Apostate Son of Fred Phelps) On Faith

Here's what I don't understand. When pressed reasonable religious folks concede that faith is what justifies their notion of god. But they all spend sooo much time learning and regurgitating all these biblical arguments that "prove" god. It seems to me if you're going to invoke faith, just stop there. No need to reason it out or rationalize. In fact a more consistent position would be to spout some gibberish then end with "therefore god!" Am I wrong?