When Israel was finally made a state, of course, that began a series of wars and battles that began almost from the first day of Israel's existence. Islam and Hinduism battled over India and Bangladesh. We filter our information about our own and other cultures to suit our images of ourselves. Since the Crusades, the bloody battles between European Christians and Muslim Turks, we have seen Islam as a formidable and barbaric opponent. For the answer to that question, one should look at the origins of both religion and war.
Humans are predators.
Like all predators, we are territorial. The purpose of the tribe is to manage and exploit resources which we could not manage and exploit as individuals. If you examine any society, you'll see that it battles other societies for control of resources, just as any two predators will fight for control of a territory. Every society has laws. Before societies organized themselves into states, laws were provided by religion.