Less mature people, quite simply, either find another religion to meet this emotional need or more likely return to the original, among feelings of peace and joy. Listen to a testimonial session at some fundamentalist church some day and you will hear this sort of story over and over. They mistake the instinct to stick with childhood indoctrination for the Holy Spirit.
I'm just describing as factually as I can what happens; where the good or bad of it all exists is beyond me.
I veer with you here (respectfully) I have seen people who were struggling with the challenges of life and religion added a reason and a way to to become the type of person they were seeking to become. My ex husband is the poster child for such a conversion. I think he is a much better person because of his religious path, but again it is how he applies it. I do not disagree that things can go terribly wrong in religion too though.
I would even agree that one that comes from a fundie environment could have a lot of anger and hate religion, I was one of those and through years and hard work/practice I have come to a place of tolerance. Would I say I was less mature, no I would say I demonstrated an incredible maturity to allow myself the process of healing and honoring where I was at( I had a longer way to go as I had to learn the actual nature of tolerance, as it was not modeled.) I'm still dealing with parents that are hard core fundies and for me it has become a grand opportunity to cultivate understanding and tolerance in all circumstances. We can only be where we are and work from there.