They live alongside each other yes, but OP's point is still valid. Muslims believe their religion is the one true religion. Christians believe their religion is

They live alongside each other yes, but OP's point is still valid. Muslims believe their religion is the one true religion. Christians believe their religion is the one true religion. And so on and so forth... Or to put it another way: they all think their shit don't stink. It's even crazier when you break it down into denominations (see: Iran vs Saudi Arabia).