I have a theory that the harder people try to convince me of something, the more it means they're really trying to convince themselves. (Example: creationism)

This seems related...

More seriously, I've seen at least one study in which it was noted that the more stringent religious sects have better retention rates, i.e., the more an ideology demands from its adherents, the more committed they are. This sounds like it could be another manifestation of the same effect.