In ‘Some Unholy Thoughts About Religion’, Dr Abb Led, PhD examines the origin of intolerance. The early humans believed in polytheism, which accommodated many Gods. For both the conquerer and the vanquished, accommodating a few more Gods wouldn’t have been a serious problem and thus there was no need to give up on ones religious affections after every skirmish or war, which in those ages might have been plenty. But Christianity changed all that. And with the coming of Islam began the complete change from poly-theism to mono-theism, which was a step backwards in the field of human relationships. For a mono-theist, accepting another God was an anathema, more so when that God happens to be associated with an enemy. That was the beginning of religious intolerance and the beginning of oppression and killing of non-believers in the name of the one God of the victor.
While examining intolerance further, the author observes that according to the psychologists the urge to convert others to one’s religious beliefs is a sign of one’s own unconscious, or even conscious, doubts. Which causes the unbelievers to be put to death. Another element common to all such groups is that, each mono-theistic religion holds ‘My religion is the only truth’. This, author says, is because each such religion has its own definition of truth, which, naturally will be aiding intolerance..