I'm sure I don't have to explain Christian theology to you. It's very sad that you have to go through this physical pain, as well losing faith as a result.
As for people who say one thing and do something else. People are fallen and hypocrites. I myself an still trying to do better, but I realize I'm still full of anger. I hope to better myself eventually.
Out of curiosity; did your spiritual life end with Christianity? Or did you continue your search?