unessential one. To say these people mass murder because they are Muslim is a vast oversimplification. There are 1.6 billion Muslims in the world yet there have been what 100 terrorist attacks globally in the last decade (including Muslim on Muslim terrorism). If it was just the nature of the religion, you'd expect far more attacks.
The nazis, bolsheviks, fascists and others all committed their atrocities without needing a religion.
Eric Hoffer wrote about this in his book, The True Believer.
Here's a few interesting passages:
Hatred is the most accessible and comprehensive of all the unifying agents. Mass movements can rise and spread without belief in a god, but never without a belief in a devil.
The burning conviction that we have a holy duty toward others is often a way of attaching our drowning selves to a passing raft. What looks like giving a hand is often a holding on for dear life. Take away our holy duties and you leave our lives puny and meaningless. There is no doubt that in exchanging a self-centered for a selfless life we gain enormously in self-esteem. The vanity of the selfless, even those who practice utmost humility, is boundless.
All mass movements generate in their adherents a readiness to die and a proclivity for united action. ... All of them irrespective of the doctrine they preach and the program they project breed fanaticism, enthusiasm, fervent hope, hatred and intolerance; all ... demand blind faith and singlehearted allegiance.
For men to plunge headlong into an undertaking of vast change they must be intensely discontented yet not destitute, and they must have the feeling that by the possession of some potent doctrine, infallible leader or some new technique they have access to a source of irresistible power. They must also have an extravagant conception of the prospects and potentialities of the future. Finally, they must be wholly ignorant of the difficulties involved in their vast undertaking. Experience is a handicap.
Link: https://www.amazon.com/True-Believer-Thoughts-Movements-Perennial-ebook/dp/B003TO5838/ref=sr_1_2?ie=UTF8&qid=1495515742&sr=8-2&keywords=true+believer