Can anyone recommend any books that cover the psychology of a believer? What makes them believe with 100% certainty that Jesus is the son of God and is alive and loves them, and they have a personal relaltionship with him. What makes them hold onto this crap so hard? Is it just brainwashing?
There's an oldie but a goodie that deals perhaps not with believers specifically, but any person or group with a razor-like dedication to their belief: The True Believer, by Eric Hoffer. Whether its religion, politics or any kind of cult of personality, it provides a powerful description of the mindset of the most determined of such followers.
Here's a good video on the topic to watch . . .
Good reasons for "Believing" in God - Dan Dennett, AAII 2007
Do yourself a favour, and watch it through, (it starts off with some awards B.S.) . . .