Sebastian Castellio and the deep roots of religious tolerance | Aeon Essays

"In terms of judicial killings in Europe, the period between 1500 and 1700 outstripped any era before or after. The new heresies of the Protestant Reformation prompted an initial burst of executions: approximately 5,000 people were put to death for their religious beliefs in the 16th century. This was followed by far deadlier witch hunts, which saw about 50,000 people legally exterminated for witchcraft."

"In the midst of this fear and uncertainty, Castellio, a professor of Greek, stepped back from the dogmatic clashes of the day. Rather than echo the calls for battle, he issued a plea for toleration. His great insight was that everyone was a heretic according to somebody else. Castellio questioned the idea of heresy itself. 'After a careful investigation into the meaning of the term heretic,' he wrote, 'I can discover no more than this, that we regard those as heretics with whom we disagree.' ... To Castellio, being 'someone with whom we disagree' was entirely insufficient grounds for being sentenced to death."

Sebastian Castellio was born in 1515 into an era marked by extraordinary judicial killings across Europe. The Protestant Reformation triggered roughly 5,000 executions for heresy in the 16th century, followed by about 50,000 legal executions for witchcraft. Shifting orthodoxies made religious allegiance politically dangerous, as rulers executed opponents when doctrines changed. Castellio, a professor of Greek, advocated toleration and questioned the concept of heresy. He argued that being deemed a heretic simply meant being someone with whom others disagreed, and he insisted that such disagreement did not justify capital punishment.

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