I've added another reason some people become skeptics to the Skeptical Fallacies page on my web site:
Research has shown that people who think analytically rather than intuitively tend to be atheists. People who analyze problems using logic, because of their education, career, or innate characteristics, may become
habituated to reductionist analysis. Reductionism is the belief that something complex can be understood by the interaction of simpler components. This way of thinking works well in many branches of science. Psychology can be explained in terms of biology, which can be explained in terms of chemistry, which can be explained in terms of physics. However, some scientists, engineers, philosophers, and other intellectuals, may become so habituated to reductionist thinking that they are unable to conceive that some phenomena cannot be explained in terms of simpler phenomena. For example, the subjective experience of consciousness, what pain feels like, or what red looks like, cannot be understood through reductionism. Psychic phenomena that cannot be explained by current scientific theories, such as telepathy, clairvoyance, psychokinesis, and precognition cannot be understood through reductionism. This is why some people who are habituated to reductionist thinking simply cannot conceive that psychic phenomena could be real or consciousness might be nonphysical and survive bodily death. Reductionists suggest consciousness is an epiphenomenon even though that is a poor explanation of consciousness because it is the best they can conceive of within their reductionist prison.