How can the brutal armies of ISIS perpetrate such crimes?

This fascinating article explains the psychology of savagery.

War bonds people together in their groups and this bonding assuages some of the terrific fear and distress the individual feels when the state breaks down. It also offers self-esteem to people who feel humiliated by their loss of place and status in a relatively ordered society. To the extent that this happens, then individual and group identities partially merge and the person’s actions become as much a manifestation of the group as of the individual will. When this happens, people can do terrible things they would never have imagined doing otherwise: individual conscience has little place in an embattled, warring group, because the individual and group selves are one so long as the external threat continues. It is groups which are capable of savagery, much more than any individual alone.

You can see it in the faces of the young male Islamic State militants as they race by on their trucks, black flags waving, broad smiles on their faces, clenched fists aloft, fresh from the slaughter of infidels who would not convert to Islam. What you can see is a biochemical high from a combination of the bonding hormone oxytocin and the dominance hormone testosterone. Much more than cocaine or alcohol, these natural drugs lift mood, induce optimism and energise aggressive action on the part of the group. And because the individual identity has been submerged largely into the group identity, the individual will be much more willing to sacrifice himself in battle – or suicide bombing, for that matter. Why? – Because if I am submerged in the group, I live on in the group even if the individual “me”, dies.

Human beings, it seems, have a default setting that (given the right circumstances) makes us prone to unspeakable violence.

Furthermore, religion makes it worse:

But here is one daunting fact as we contemplate the Sunni-Shia carnage in Iraq and Syria: in-group tribalism is strengthened – and loathing for the out-group correspondingly increased – where religion defines the groups. Even when aggression against the other group is self-destructive – as we can see so tragically across the Middle East – religiously-based groups advocated a degree of aggression against their opponents which was absent in non-religiously defined groups.

Of course. When you believe God is on your side, then you can not only commit horrible crimes, but you feel righteous for doing so. This is the “blame dynamic” I wrote about here. The “out group” is scapegoated, and once they are objectified and the evil is put on them, the religious person feels righteous for destroying them. It is happening on a macro scale with ISIS. It happens on a micro scale when we gossip about a person and destroy them.

Read the whole article here