It seems that religion is the fount of hatred. After listing a catalogue of horrors, James A. Haught says,
…people who think religion is a force for good are looking only at Dr. Jekyll and ignoring Mr. Hyde. They don’t see the superstitious savagery pervading both history and current events.
During the past three centuries, religion gradually lost its power over life in Europe and America, and church horrors ended in the West. But the poison lingered. The Nazi Holocaust was rooted in centuries of religious hate. Historian Dagobert Runes said the long era of church persecution killed three and a half million Jews — and Hitler’s Final Solution was a secular continuation. Meanwhile, faith remains potent in the Third World, where it still produces familiar results.
It’s fashionable among thinking people to say that religion isn’t the real cause of today’s strife in Lebanon, Sri Lanka, Northern Ireland, India and Iran — that sects merely provide labels for combatants. Not so. Religion keeps the groups in hostile camps. Without it, divisions would blur with passing generations; children would adapt to new times, mingle, intermarry, forget ancient wounds. But religion keeps them alien to one another.
Anything that divides people breeds inhumanity. Religion serves that ugly purpose.