Distance creates traditions and traditions creates relegions, some choose different way of practising those traditions and finally create a religion. In India every 100-200 KMS traditions and language changes, that is why you have so many religions in India, Now consider world how many traditions and religion are there, there are religious heads with a difference of opinion and it creates the problem. If you convert all people of this earth to a single religion, see after 50 years or add more years to it, they will practise it differently, because there is no common body which will govern their way of worship. And finally they will create their own religion. This is nature which governs the religion not humans. Not a single religion today is without a divide among themselves. Forget fighting for a religion. You see a single joint family also, division is penetrated them so deeply, then forget about the whole religion which is composed of a million people. A difference of opinion creates a divide. Europeans fought over religion and colour and had so many wars. Now they got it, Ashok the Great also fought finally he understood there is no use fighting. And if you say my religion is true, then forget it you cant justify why you do that. Keep your religion inside you house/home, dont impose on anyone, it is for you not others.