Mandatory relevant Douglas Adams:

"I refuse to prove that I exist,'" says God, "for proof denies faith, and without faith I am nothing." "But," says Man, "The Babel fish is a dead giveaway, isn't it? It could not have evolved by chance. It proves you exist, and so therefore, by your own arguments, you don't. QED." "Oh dear," says God, "I hadn't thought of that," and promptly vanishes in a puff of logic.