The March issue of Scientific American contains an article by Michael Shermer that cites a study published in the December 2007 Annals of Neurology:
Shermer is a professional skeptic, and perhaps takes his skepticism farther than I would; I'm not sure that he is necessarily a fan of religion in general, for example. That being said, I think if it is the case that most people have a low tolerance for ambiguity, then he raises an interesting point, one that explains a great deal about the appeal of religious fundamentalism, with its lack of tolerance for ambiguity, metaphor, uncertainty and symbolism. But with Easter just around the corner, I think it also explains how it is that many people can come to believe that 2000 years ago a corpse was resuscitated, walked around for 40 days, and then apparently without even so much as a jetpack on his back was lifted vertically off the earth into the sky into a heavenly realm that is physically located above the clouds.
This research supports Spinoza’s conjecture that most people have a low tolerance for ambiguity and that belief comes quickly and naturally, whereas skepticism is slow and unnatural. The scientific principle of the null hypothesis—that a claim is untrue unless proved otherwise—runs counter to our natural tendency to accept as true what we can comprehend quickly.