If you're into psychology it's really easy to work it out in my opinion, you're just not supposed to say anything about it because people get offended. But there's no surprise;
It's down to multiple things, but mostly the idea that this life doesn't matter, they're just waiting to go to heaven or whatever. It doesn't matter how bad this life gets, or the fact they could change it to be better, they rely on the idea there is a better place for them.
That allows people to justify a lot of behaviours, especially with what the Bible or the like would consider moral and immoral, and how it can be interpreted however one wishes. Its written word its more open to interpretation than any other form of communication.
You also have the idea of destiny, fate, gods plans, nothing you do matters because everything is already preordained so you'll end up where your supposed to be anyway.
If someone is weak of mind, that sort thinking can **** one up.
I could go on but I'm running out of room.