Because the critical component in organized religions is social control, and one of the most critical factors in social control is maintaining the 'social proof

Because the critical component in organized religions is social control, and one of the most critical factors in social control is maintaining the 'social proof field'. If everyone believes something it enhances the belief, but if there are non believers they diminish the social proof field in the vicinity of their social graph. Alone these 'heretics' are not a threat, but as soon as two get together it's no longer about one lunatic deviant who you can ignore, but a social phenomenon. The more you have heretics the stronger their social proof field becomes, enticing people away. Religions are much more understandable as social movement and political constructs that lean heavily on propaganda rather than as methods of investigation into the nature of reality.