The Psychology of Religion, Chapter 21: Historical Atrocities

Humans have engaged in every manner of atrocity, and despite the horrors of the past century, we see repeatedly—across earlier centuries as well—how easily cruelty can be normalized, ritualized, and justified. The human capacity for harm is ancient. What is especially sobering is how often the major religions have managed to make cruelty feel righteous. Faith is not the sole author of human violence, but that it has proved extremely effective at sanctifying it.

Many historical atrocities have occurred under the banner of religion, especially when religious identity fused with conquest, state power, or tribal domination. Charlemagne’s campaigns against the Saxons (772–804) are an early example, fusing military conquest with forced Christianization. Saxon resistance was treated as defiance of Christian rule. Forced conversion was backed by severe legal penalties—including death for refusing baptism, as set out in the Capitulatio de partibus Saxoniae—and the suppression of Saxon resistance led to episodes of mass killing, including the notorious Massacre of Verden in 782, where 4,500 Saxons were reportedly beheaded in a single day.

The Crusades (1095–1291) likewise included mass killing justified in religious terms. The Rhineland massacres of 1096 saw crusader mobs fall upon the Jewish communities of Speyer, Worms, Mainz, and Cologne, forcing conversion or death. And when Jerusalem fell in 1099, Muslims and Jews were slaughtered.

The Thirty Years’ War (1618–1648)—which began as a struggle between Catholic and Protestant rulers within the Holy Roman Empire before widening into a broader conflict—became one of the most devastating catastrophes in European history. Ending with the Peace of Westphalia, it killed several million people and laid waste to wide stretches of central Europe, with some German territories losing a third or more of their population and the worst-hit areas more than half.

The Spanish Inquisition (established in 1478 and not abolished until 1834) built a machinery of religiously motivated coercion and intimidation. It targeted conversos—Jews who had converted to Christianity, often under intense pressure—and later Moriscos, Muslims who had likewise been baptized, as well as Protestants. The exact death toll is debated—modern estimates put the executions in the low thousands, far below the figures of popular legend—but the essential point is not: it was a system designed to enforce conformity through fear, punishment, and, in many cases, execution.

Other episodes fit the same pattern. The witch hunts of early modern Europe and its colonies, which I discussed in an earlier chapter, ran from the fifteenth to the eighteenth centuries and produced perhaps 100,000 trials and around 45,000 executions, the great majority of the victims women. These persecutions were not merely random superstition; they were tied to a specifically Christian demonology that linked “witchcraft” to heresy, to Satan, and to a cosmic struggle against evil. The same logic appeared in campaigns against peoples classified as pagan or heathen. In the Baltic Crusades, military orders such as the Brothers of the Sword and later the Teutonic Knights pursued conquest together with Christianization, and forced conversion was part of the programme. In Muslim history, the language of jihad was at times used to frame warfare—but it should be emphasized that jihad does not simply mean “holy war,” and in Islamic thought it has long encompassed moral and spiritual struggle as well.

Colonial movements in later centuries often used religious language—“civilization,” “salvation,” missionary uplift—as moral cover for extraction and domination. Leopold II’s Congo Free State (1885–1908) was not simply a Belgian colony but effectively Leopold’s personal possession. It was presented as a humanitarian venture that would end slavery and bring religion and modern life to the Congolese. In practice it became a regime of forced labour, hostage-taking, mutilation, and terror, likely causing millions of deaths, though the exact figure is disputed. It was wrapped in Christian and “civilizing” rhetoric, and missionaries were part of that colonial world—though many of them later helped expose the abuses.

The transatlantic slave trade and the slavery it fed (spanning roughly the sixteenth to the nineteenth centuries) were likewise defended by many religious leaders and institutions, often through distorted readings of scripture. One recurring example was the so-called “Curse of Ham”—in fact Noah’s curse on his grandson Canaan, later twisted into a supposed justification for African slavery—even as other religious figures, the Quakers most prominently, became central to the abolitionist movement. The point is not that religion uniquely caused the exploitation, but that it was repeatedly available to sanctify it.

The same pattern appears in Canadian history. “Christianization” was one motive—alongside the state’s assimilationist policy—behind the residential school system. Church-run schools began earlier, but by the 1880s the federal government had adopted an official policy of funding residential schools across the country, and the last did not close until 1996. More than 150,000 First Nations, Inuit, and Métis children passed through these church-run, state-funded institutions, which were designed to sever children from their families and cultures and were marked by widespread abuse. Thousands died, and the records remain incomplete.

The Spanish conquest of the Americas, beginning with Columbus in 1492 and intensifying with Cortés’s overthrow of the Aztec empire in 1519–1521, likewise brought catastrophic Indigenous death and cultural devastation. Disease accounted for much of the mortality, but religious institutions were deeply entangled with the colonial project. Conquerors often invoked the Requerimiento—an official legal demand, drafted by Spanish authorities and read aloud before conquest, which asserted the Pope’s authority and Spain’s claim to the land, demanded submission to the Crown and acceptance of Christian preaching, and threatened war, enslavement, and dispossession for refusal. In practice it was frequently read—in Spanish or Latin—to people who could not understand a word of it, sometimes with no translation at all. To be fair, some clergy, most famously Bartolomé de las Casas, later fought publicly against the abuse of Indigenous peoples.

It would be a distortion, though, to leave the impression that this is a Christian failing in particular. The examples above are drawn largely from the Christian West, because that is the history I know best and the record most fully documented in the languages I read—not because other traditions have been innocent of the same logic. The pattern recurs across the religious world. Buddhist nationalist movements in Myanmar and Sri Lanka—the tradition most often imagined in the West as constitutionally peaceful—have in recent years inflamed mob violence and persecution against Muslim minorities. Hindu nationalism has been entangled with deadly communal violence in India. Warfare and persecution have repeatedly been waged in the name of Islam, which has also been riven by its own lethal divisions. The scholarly literature on religious violence now spans every major tradition; none has clean hands.

Of course, violence and atrocity have flourished outside religion as well, and the secular ideologies of the twentieth century—fascism, Stalinism, Maoism—justified horrors of their own on an industrial scale. So the claim here is not that religion is the uniquely guilty party in the long history of human cruelty. The claim is narrower, and I think harder to dodge: that religion has repeatedly proved able to take ordinary, decent people and persuade them that cruelty is holy—and that it has plainly not been a reliable protection against humanity’s worst impulses. Cruelty, as I argued earlier, does not originate in belief. But belief has been remarkably good at blessing it.

References

Goldenberg, D. M. (2003). The curse of Ham: Race and slavery in early Judaism, Christianity, and Islam. Princeton University Press.

— Traces how the Genesis story of Noah’s curse on Canaan was gradually transformed, in extra-biblical interpretation, into the “Curse of Ham” used to justify the enslavement of Africans. Goldenberg shows the racial reading is absent from the text itself and emerged later; Stephen Haynes’s Noah’s Curse covers its American afterlife.

 

Hochschild, A. (1998). King Leopold’s ghost: A story of greed, terror, and heroism in colonial Africa. Houghton Mifflin.

— The standard popular history of Leopold II’s Congo Free State, documenting the forced-labour rubber regime and its vast death toll, as well as the missionaries and reformers who exposed it. Hochschild calls the killing “of genocidal proportions” while noting it was not, strictly, a planned genocide.

 

Juergensmeyer, M. (2003). Terror in the mind of God: The global rise of religious violence (3rd ed.). University of California Press.

— A comparative study of religiously motivated violence across Christianity, Islam, Judaism, Hinduism, Sikhism, and Buddhism, arguing that the sacralisation of conflict is a cross-traditional phenomenon. No major religion has been exempt; for the Buddhist cases specifically, see also Jerryson and Juergensmeyer’s Buddhist Warfare (2010).

 

Kamen, H. (1998). The Spanish Inquisition: A historical revision. Yale University Press.

— The leading revisionist history, which dismantles the inflated “Black Legend” figures and places executions over the Inquisition’s full span in the low thousands. Kamen situates the institution within its political context without minimising its machinery of fear.

 

las Casas, B. de. (1992). A short account of the destruction of the Indies (N. Griffin, Trans.). Penguin. (Original work published 1552)

— The Dominican friar’s eyewitness denunciation of Spanish cruelty toward Indigenous peoples, addressed to the Crown. A foundational document of conscience from within the colonial Church, and the most famous contemporary protest against the conquest.

 

Levack, B. P. (2006). The witch-hunt in early modern Europe (3rd ed.). Pearson Longman.

— The standard synthesis of the European witch trials (c. 1450–1750). Careful regional accounting yields a consensus near 45,000 executions out of roughly 100,000 trials—far below the figures of popular legend—and locates the persecutions within Christian demonology and the law.

 

Truth and Reconciliation Commission of Canada. (2015). Honouring the truth, reconciling for the future: Summary of the final report of the Truth and Reconciliation Commission of Canada.

— The official summation of Canada’s residential school system, which it characterises as “cultural genocide.” It documents the more than 150,000 children who passed through the church-run, state-funded schools, the thousands who died, and the incompleteness of the records.

 

Tyerman, C. (2006). God’s war: A new history of the Crusades. Belknap Press of Harvard University Press.

— A comprehensive single-volume history of the crusading movement, covering the Rhineland massacres of 1096 and the slaughter that followed the fall of Jerusalem in 1099, as well as the theology that framed holy war.

 

Wilson, P. H. (2009). The Thirty Years War: Europe’s tragedy. Belknap Press of Harvard University Press.

— The definitive modern history, which stresses that the war was as much dynastic and political as confessional, and assesses the demographic catastrophe—on the order of a quarter of the German population—without recourse to the most exaggerated figures.

 

A note on primary documents (handled as sources rather than formal citations): the figure of 4,500 executed at Verden comes from the Royal Frankish Annals; the death penalty for refusing baptism is set out in the Capitulatio de partibus Saxoniae (c. 782–785); the conquest demand is the Requerimiento of 1513, drafted by Juan López de Palacios Rubios; and the scriptural passage behind the “Curse of Ham” is Genesis 9:20–27, in which Noah curses his grandson Canaan.

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