People of Religion......................…

There are several reasons. One can be due to tribalist mentality. People from all nations or social organizations have an inherent tendency to believe that that they are "the best" and that their way is the "only one true way". Second reason would be that they dogmatically follow the writings of their religion literally. You gotta be more open when you read things about religion. Third reason would be that they are too used to following what they are taught that they rely on feelign secure and comfortable with the thought of absolutism.