I. The Tradition of Religious Intolerance

From early Christianity, Western society inherited a powerful and conscious tradition of religious intolerance. Christian commitment was exclusivistic. It proclaimed itself to be the only true faith, and regarded itself as eligible for the universal allegiance of all mankind. It was a voluntaristic faith, and to the end of converting and embracing the whole of humanity it was from the outset committed to relentless proselytising. This unique constellation of attributes differentiated early Christianity from other contemporaneous religious movements; from Judaism, which was ethnically based, and from the prevalent mystery and emperor cults which were tolerant of, or at least indifferent towards other religions. Medieval Christianity maintained its aggressive proselytising against pagan and heathen religion, the votaries of which were to be converted, but developed an even more rigorous policy of suppression of all wayward or heretical manifestations of Christian belief. Heresy was punishable by death—a policy theologically justified by Thomas Aquinas (1225–74) and relentlessly implemented by the Inquisition (instituted in 1232 and finally suppressed, in Spain, only in 1820). The Reformation brought some, albeit gradual, diminution of the grosser forms of religious intolerance, but hostility towards “deviant” expressions of Christianity persisted even in the most liberal and advanced of Protestant countries.

II. The Experience of “New” Movements