Abstract

Most theists do not put a (subjective) probability of 1 (certainty) on God's existence. Most atheists do not put a probability of 0 on God's existence. I argue that these familiar positions are incoherent. On the assumption of S5 and the probability calculus it can be shown that the only coherent (subjective) probabilities an agent can assign to God's existence/non-existence are 0 or 1. Believers must be completely committed believers and non-believers must be completely committed non-believers. Agnosticism is not a coherent position.