A God susceptible of proof would wither and starve the spirit of mysticism. Such an entity would be finite and limited. It would be one thing among other within the universe; a thing bound by identity and causality capable of being integrated without contradiction into man’s cognitive context, incompatible with miracles, revelations and the other paraphernalia. Such an entity would not be an inevitable mystery transcending nature and science, it would be a part of nature to be studied by science, and it would be of no use whatever to a mystic.

- Leonard Peikoff.