What are the psychological and sociological factors that cause religious belief to be so strong that many people cling to it over rational thought?
I don't know about other christians, but I grew up scared to death that if I didn't go to church and read my bible and follow the ten commandments, I was going to burn in hell forever. That fear will take over any rational thought anytime. Since I have abandoned my Christian faith, there is not much that frightens me anymore.
Because religion is a manipulation of emotions, not rationality. Get a person addicted to feeling a certain way, or traumatized by horror stories of burning alive preventing him/her from questioning it, and it will be very hard to rationalize those emotions away.
Secondly, a lot of people raised in religion have said religion wrapped around every aspect of their lives. Meaning breaking free of it will force you to reexamine all the things you feel comfortable and familiar with. Including the people in your family.
Psychologically, when people have a problem it's hard to conquer it if they are entwined with the problem. If they are a part of the problem it's hard for them to accept that and find a solution. So, believing in religion is actually a form of externalization. What a problem is externalized, you could talk about it and conquer it much more easily. For example, fear is having an effect on me vs I'm so scared I can't do it. It's more empowering to externalize something and then take care of something.
It's my belief that some people don't have the self-control to get their shit together on their own. Some people need to believe that there's a higher power up there that expects them and wants them to do certain things. So, they do the right thing for the higher power rather than hold the responsibility themselves, and possibly not do the right thing because there is no one holding them accountable but themselves.