Looks like you've had quite the response!
I have two pieces of advice for you:
(1) If he is a wonderful man - then he deserves to be free from that religion. Don't jump into the quick sand with him - throw him a life line and help him OUT
(2) You indicated that you don't know much about bible. Don't try to learn it from a cult - go to the source itself. Pick up a bible and start by reading the book of John. It's an easy book to read and encompases the message of Jesus.