Religion versus Barbarism

It is said that one of the functional virtues of religion is that it helps to lift us out of barbarism. I grant that sometimes it does. But it's a mixed bag Here, René Grousset compares the devastations inflicted by Tamberline in the 15th Century with those of his predecessor Genghis (Jenghiz?) Khan in the 13th.

It has been noted that the Jenghiz-Khanite Mongol invasion of the thirteenth century was less cruel for the Mongols were mere barbarians who killed simply because for centuries this had been the instinctive behavior of nomad herdsmen toward sedentary farmers. To this ferocity Tamerlane added a taste for religious murder. He killed for piety. He represents a synthesis, probably unprecedented in history, of Mongol barbarity and Muslim fanaticism and symbolizes that advanced form of primitive slaughter which is murder committed for the sake of an abstract ideology, as a duty and a sacred mission.

--René Grousset, The Empire of the Steppes:
A History of Central Asia 434 (Trans. 1970)

Earlier, Grousset has argued that Mongol warfare, however savage, was more "natural," in that it was a matter of nomadic warriors preying on their richer settled brethren, using techniques they had developed in the hunting of (other?) animals.