In Hitch-Hiker's guide to the galaxy it argues that the very act of god proving himself would prove he doens't exist - becasue he can't exist without faith and if people need proof he exists then they don't have faith. So by proving he existed he would, in fact, be proving he doesn't exist.

This is, according to hitch-hiker, why the earth itself is proof that god doesn't exist. Becasue something so complicated would be proof that God exists, so it is therefore proof that he doesn't.

Or something ike that. I understand where I'm going with this anyway! (I don't have the book here right now - you may have noticed!)