Sometimes, heretical takes on Christianity could drive a mob to violence, but on occasion, church authorities themselves orchestrated violence very deliberately. One of the intellectual superstars of fifth century Egyptwas a brilliant woman called Hypatia, a scientist and philosopher. Her religious skepticism (and her gender) angered the city’s bishop, Cyril, whose political position allowed him to do more than just fume quietly in his palace. In particular, he commanded the loyalty of a turbulent army of monks who would do anything for the honor of their faith and their church. Whether or not Cyril gave the order, in 415, the monks lynched and dismembered Hypatia. Cyril, oddly, is now venerated as a saint.

Monks as militias

Nor was such a criminal outrage a freak or rare event. In the fifth and sixth centuries, Christian monks served as private militias, holy head-breakers whom charismatic bishops could turn out at will to sack pagan temples, to rough up or kill opponents, and to overawe rival theologians. These were not rogue monks or clergy gone bad but loyal followers of the churches, doing exactly what was expected of them. When cities or regions divided along lines of theology or faith, as they often did, rival bishops and monks literally fought for domination in the hills and on the streets. Bishops mobilized an impressive amount of muscle to promote their causes, making them powerful independent political actors. Between 450 and 650 AD, during what I have called the “Jesus Wars,” inter-Christian conflicts and purges killed hundreds of thousands, and all but wrecked the Roman Empire.

Reading such stories of religious violence today, most of us naturally think of Islamic extremism, which finds such a convenient face in the mullahs and ayatollahs who have become so notorious in Iran, Afghanistan, Iraq and Lebanon. During the recent Iraqi elections, for instance, the Obama administration was dismayed to see the enormous strength of Shiite leader Muqtada al-Sadr, a celebrated cleric who uses his paramilitary Mahdi Army to control whole cities. And from there, it is not too large a jump to assume that the rampant violence of such countries, all the intolerance and fanaticism, must be deeply rooted in the faith of Islam. Perhaps, we think, Islam never has recovered from the warlike teachings of the Quran, which stands in such sharp contrast to the peaceful words of the Bible. Moreover, Islam apparently demands slavish devotion to charismatic holy men. Some observers even ask whether Islam can ever be compatible with a peaceful and democratic society.

‘Anathemas’ or ‘fatwas’

But reading Christian history suggests just how wrong just an analysis would be. Out-of-control clergy, religious demagogues with their consecrated militias, religious parties usurping the functions of the state — these were the common currency of the Christian world just a few decades after the Roman Empire made Christianity its official religion. Whatever he might have thought of his theology, Cyril the Christian bishop would immediately have a strong fellow-feeling for al-Sadr the Islamic mullah. Like al-Sadr, Cyril, too, disciplined his followers with pronouncements that cast deviants beyond the protection of the church and the law: Christians then called them “anathemas”; Muslims today call them “fatwas.”

In retelling the story of Christian atrocities, I’m not trying to blacken the reputation of the church but rather to suggest that, given the appropriate social and political circumstances, given a sufficiently weak state mechanism, any religion can be used to justify savagery and extremism. None of the violence or intolerance commonly seen in modern-day Islam is, so to speak, in the DNA of that religion, any more than of Christianity. Change the circumstances, and any religion, too, can become the basis of a sane and peaceful society.

Philip Jenkins is the author of Jesus Wars and The Lost History of Christianity. He has a joint appointment as the Edwin Erle Sparks Professor of the Humanities in history and religious studies at Penn State University and as Distinguished Senior Fellow at the Institute for Studies of Religion at Baylor University.