Because when it comes to religion, most people told that THEIR way is the right way. And that people who say otherwise are the sinners, or the fiends, heathens, whatever. In the middle-east, there is not huge exposure to other religions, because most people there are religious-radicals, their religion takes up their whole life. They are also told that their religion is the only correct way, and are sometimes told that others who think otherwise need to be terminated or persuaded to their own religion.
I hope this helped. :)
