I was reading my Powell's newsletter and found this fascinating essay by a former missionary in the Amazon. In it he speaks about his experiences as a linguist and Christian, and how he lost his belief in Christianity.
When I used to teach international students in an intensive program we would do a lot of cultural awareness activities. I was interested in how some students could be immersed in a new culture but not influenced by it, and how other students would be completely knocked off their foundation. It sounds like the latter happened to this guy.