If you have the time, this is an interesting if not profound article in the weekend New York Times Magazine on the scientific explanation as to why humans believe in God.
Have humans evolved to believe in God?
For secularists, humanists and the religious alike . . . . . and maybe an unintended sidebar look into the psychology of conspiracy theorists as well:
http://www.nytimes.com/2007/03/04/ma...=1&oref=slogin
Cowperson