I have wondered about that. I believe that a lot of them do believe. But I think that the higher up you go in any religious hierarchy, the more people do it for power and not because they still have faith.
A guy I dated once, said his mom was very religious. And she was going on about all this uber religious stuff one time, and her father, who had fed it to her as a child, said, "Holy cow, do you still believe all that crap?"
They were Catholic.
"Fun must be always." - Tomas Hertl, San Jose Sharks
"It was fun." - Kirk, Star Trek: Generations