Since the topic of atheism, morality, and the like often come up here, I would like to point people to the free online book Secular Wholeness by David Cortesi. He approaches the topic of religion by trying to determine what benefits it can provide (community, challenges to improve oneself, easier ethical decisions, etc.), then tries to describe how to achieve these same benefits without resorting to religion. It's not very heavy on detail but seems very well sourced and with some good pointers on why people choose religions and what they get out of them.

ETA: This could have been a reply to the thread on Scientology, had I seen it before posting.