You can speculate all you want but you can never truly know until you ask them, which I don't think you'll ever get the chance to do. My assumption would be, they may be troubled in life, and fighting serves as an aggression outlet while have strong religious beliefs helps them with any inner turmoil.
This may not have anything to do with it, but it leads to the same point. Humans intend to get closer to him in situations like that especially knowing you're about to die.
Because they have been hit in the head one to many times,lol. Just last night Vitor Belfort thought God was going to help him win, but his opponent believes in the same God. It doesn't take a genius to see the glaring problem with that scenario.