Debates between theists and atheists often hinge, naturally enough, on advances in cognitive neuroscience and evolutionary biology. Here I contend that such advances, though relevant to the debate, cannot license deductively valid arguments for or against theism. I contend further that the central role of probability in evolutionary theory grants no inductive strength to arguments for or against theism. The Kolmogorov axioms of probability and the mathematical definition of a stochastic process suitably model mutation and selection; using this fact to conclude for or against theism requires, in either case, a leap of faith.