I've pointed out a number of times that the extent of one's religiosity has a large biological component. Not what religion but how deeply religious is heritable. In a recent study, researchers gave personality tests to people before and after surgery to remove a brain tumor. The tests specifically measured "the personality trait called self-transcendence," which "reflects a decreased sense of self and an ability to identify one's self as an integral part of the universe as a whole."
They found that damage to the left and right posterior parietal regions caused an increase in self-transcendence. The authors say what's important about this is that a stable personality trait can be affected by a lesion in the brain, then maybe we could find ways to affect the brain to alleviate personality disorders. (Insert obligatory praise of what science can do for us and caveat about Big Brother here.)