I believe that people don't understand why things happen the way they do. They join these groups for the same reasons that people join gangs - because they want to belong. They want to feel taken care of. They don't want to feel alone. They want to feel like someone is watching out for them. They like the myth that there will a reward in the end for all their suffering. My husband had a aunt who had a facial deformity and she found solace in church. At least she could fool herself into believing that there was a reason she had her deformity. It is easier than to believe that you just were unlucky.
We have a Mormon neighbor. Once we started talking politics. He said he didn't know who he was going to vote for. He was going to ask the people at church who he should vote for. I'm not saying that there aren't Mormons who think for themselves, but in this particular case, I thought it was sad that he didn't think he could make his own decisions, which I think is another reason people join these groups - they let someone else take responsibility, so they can act like a child again.