The simplistic answer is that certain religions are inherently violent, but this is not that useful of a response, because in truth, every religion can be fashioned into a weapon which people can wield to justify murder and conquest.

As far as I can tell, religious dogma isn’t really that much different from secular political/ideological dogma. (If you have any doubt about that, just look at the Communist Parties in the USSR, the PRC, and the DPRK.) If anything, demands for adherence to religious dogma is primarily driven by political power plays.¹

I honestly think you can gain more insight into terrorist attacks when you look at them primarily in political terms. Don’t get me wrong, religion can certainly be used as a cattle prod to get people to commit atrocities, but the aims are always political.²

Oh, for sure, some people’s political aim is to create a theocratic utopia. Hell, we have some people in this country running for elected office on that kind of platform. But it doesn’t really matter what religion is used as justification in the quest for power.³

And it’s not just the leaders of ISIS you need to look at. You also need to look at the political aims and goals of the people who fund and arm ISIS and the people who look away while money and guns change hands.⁴

• Who funds the ISIS Islamist militants in Iraq? • 2014 Jun 18 • The Telegraph
• Startling revelations: IS operative confesses to getting funds via US • 2015 Jan 28 • Naveed Miraj • The Express Tribune
• Islamic State: The Economy-Based Terrorist Funding • Jean-Charles Brisard and Damien Martinez • Thomson Reuters Accelus
• Here’s How The World’s Richest Terrorist Group Makes Millions Every Day • Amanda Macias and Jeremy Bender • Business Insider

via How is ISIS funded and how do they operate? • Quora