The cheerleader effect is a cognitive bias that causes people to appear more attractive in a group. I'm no expert on psychology, but I have a theory that a similar phenomenon exists for beliefs. By compiling a list of beliefs you make them appear more reasonable, however, if you actually break one away from the herd and really break it down you can easily discover what an illogical mess it truly is.
I first noticed this when I debated with my father on the subject of the Bible, oftentimes when I would make a valid argument against the Bible he would say something along the lines of, "and that is enough to make you forget about such and such" (usually the "accuracy" of Bible "prophecy" or the good effect the Bible has on people's lives). I think that phenomenon may be part of what is responsible for allowing religious groups like the Jehovah's Witnesses to survive so long in an era where information is so readily available.