I think it was when I ran into Kerouac and Burroughs - when I was 17 - that I realized I was talking through an empty skull... I wasn't thinking my own thoughts or saying my own thoughts.
I mean the word proof not in the sense of the lawyers, who set two half proofs equal to a whole one, but in the sense of a mathematician, where half proof = 0, and it is demanded for proof that every doubt becomes impossible.
To philosophical materialists God is no more than an idea in the human mind, and not a very important idea.