It comes up in almost every conversation with a skeptical friend, usually stated as settled fact: religion is the great engine of human violence, the Crusades and the Inquisition just the warm-up acts for a habit that has never really stopped. It sounds true because it is repeated so often. It also happens to be false.
The direct answer: no. Christian apologist Alycia Wood points out that the bloodiest century in human history, the twentieth, was driven overwhelmingly by secular and explicitly anti-religious regimes, not religious ones. The deeper problem was never religion itself. It was human nature operating without anyone to answer to.
Where Does the Claim That Religion Causes Most Wars Come From?
The charge has a famous, quotable version. Physicist Steven Weinberg argued that without religion you still get good people doing good and evil people doing evil. The moral math stays roughly the same either way. But for genuinely good people to commit genuinely evil acts, in his view, takes religion.
For good people to do evil things, that takes religion.
— Steven Weinberg, as quoted by Wood
It is a clean line, and it has stuck around for decades of debate because it sounds like it explains something. Notice what the line is actually doing. It is not really a historical claim, even though it gets used as one. It is a rhetorical move that lets the speaker explain away every other source of mass violence in human history while keeping one institution on the hook for all of it. That move only works if nobody checks the math behind it.
Wood’s response is not to get defensive about church history. The Crusades happened. The Inquisition happened. Pretending otherwise would not be honest and would not be necessary. Her response is simply to ask whether the sweeping claim, that religion causes most of history’s violence, actually survives contact with the record once you look at the deadliest century on file.
What Does the Twentieth Century’s Death Toll Actually Show?
Wood lays out the body count plainly. The First World War killed roughly fifteen million people. Stalin’s Soviet Union killed roughly twenty million of its own citizens. The Second World War killed roughly fifty-five million. Mao’s Communist China killed roughly forty million more. None of these were religious wars. Several of the regimes responsible were explicitly hostile to religion, treating it as a problem to be eliminated rather than a cause to be advanced.
Atrocities do not just happen in the name of religion.
— Alycia Wood
This is not an argument that religious violence never happened, and Wood does not need to deny it. Her point is narrower and harder to dismiss: if you are looking for the single biggest driver of mass atrocity in modern history, the evidence points away from religion, not toward it. The agnostic writer David Berlinski put the same observation more dryly. He listed the worst tools humanity built for killing itself (poison gas, barbed wire, eugenics, the formula for Zyklon B, intercontinental missiles and nuclear weapons) and asked who handed us all of it.
If memory serves, it was not the Vatican.
— David Berlinski, as quoted by Wood
Berlinski is not a Christian making a defensive case for his own team. He is an agnostic mathematician and philosopher, which is part of why Wood reaches for his line. It is one thing for a believer to insist religion gets unfairly blamed. It is another thing entirely when a skeptic, with no stake in defending the church, looks at the instruments of the twentieth century’s worst killing and traces them back to laboratories, ideologies and governments that had nothing to do with a pulpit.
If Not Religion, What Actually Drives Atrocity?
Here is the obvious follow-up: if religion is not the engine, what is? Wood points to research by psychologist Jesse Bering, who is himself agnostic, on what actually restrains bad behavior. In one well-known study, children left alone with a game cheated freely when no one was watching. Add an adult to the room, or even tell the children a make-believe princess was watching invisibly, and cheating dropped sharply. Bering’s conclusion was that a sense of being watched by some moral, all-seeing presence pushes behavior toward good, regardless of whether the presence is real.
Wood adds a modern, lower-stakes version of the same pattern. People say and do things through anonymous online accounts (harassment, cruelty, exposure) that they would never attempt under their own name and face. Remove accountability, and behavior changes, often for the worse, with or without religion anywhere in the picture.
Who are you when no one is watching?
— Alycia Wood
Run that question against the twentieth century’s worst regimes and the pattern holds. Removing religious restraint did not produce a gentler century. It produced some of the deadliest regimes in recorded history, several of which removed religion specifically because it stood in the way of total control.
Does This Mean Atheists Cannot Be Good People?
No, and Wood is careful to say so plainly. She is not arguing that unbelief makes a person violent, or that belief automatically makes a person good. Plenty of nonreligious people live honest, generous lives. Her claim is narrower than that and harder to wave away: removing accountability to anything beyond ourselves does not make humanity as good as it likes to imagine. The twentieth century is the data set. It tested what happens at scale when entire societies decided no one was watching, and the results were not an improvement.
Joseph Byamukama’s work on traditional African religion adds a useful angle here. He has pointed out that most cultures across history, with no contact with each other, independently arrived at belief in one supreme creator who sees and judges human conduct. That is hard to explain as pure coincidence, and it lines up with Wood’s deeper point: human beings seem wired to function better, and to know it, under the sense that someone is actually watching.
This also reframes what secular violence actually proves. The twentieth century’s worst regimes were not accidentally secular while also happening to be murderous. Several of them, the Soviet Union under Stalin chief among them, treated religion as a rival authority to be actively suppressed, precisely because a transcendent moral standard above the state is inconvenient for a state that wants total control. Remove the sense of a watching God, and you do not get a morally neutral vacuum. You get whatever fills the space instead, and history suggests that what fills it is rarely gentler.
What Does Justin Brierley’s Research Suggest About a Secular Alternative?
Justin Brierley, who spent years hosting debates between believers and skeptics, has made an observation that fits naturally alongside Wood’s. He argues that human beings are not built to live inside a do-it-yourself story, one they author entirely on their own terms with no larger framework holding it up. People who try anyway tend to import a substitute framework (a cause, an ideology, a movement) that ends up functioning exactly like a religion, complete with its own version of sin, salvation and judgment, just without calling it that.
The twentieth century’s secular ideologies followed that pattern closely. Communism, fascism and other totalizing systems did not eliminate the human hunger for ultimate meaning and ultimate authority. They redirected it toward the state, the party or the leader, often with even less restraint than religious frameworks typically apply to themselves, since there was no higher court left to appeal to.
How Should This Change an Actual Conversation?
Knowing the numbers is not the same as knowing how to use them well. The temptation, once you have the death toll memorized, is to deploy it as a conversation-ending mic drop: you are wrong, here are the facts, debate over. That approach usually produces a defensive opponent rather than a persuaded one, which defeats the actual purpose of correcting the record in the first place.
A better use of the same information is as an honest question rather than a rebuttal. If the deadliest century in human history was driven mostly by attempts to remove religious authority rather than enforce it, what does that suggest about human nature once accountability is taken off the table entirely? That question invites someone to think alongside you rather than defend a position against you, and it is closer to what Wood is actually doing in her own teaching. She is not trying to win a point about the Vatican’s comparative innocence. She is trying to relocate the conversation from an institution’s track record to the human heart’s track record, which implicates everyone in the room, believer and skeptic alike.
Quick Answers
Has religion caused most of history’s wars? No. The twentieth century’s worst death tolls came overwhelmingly from secular and explicitly anti-religious regimes.
What about the Crusades and the Inquisition? Wood does not deny religious violence happened. Her point is that it is not the main driver of history’s deadliest atrocities.
So what does cause atrocity? Human nature operating without accountability. Research shows people behave worse when they believe no one is watching.
Can people be good without believing in God? Yes, and Wood says this directly. Her argument is that removing accountability does not make humanity as good as it assumes.
Listen to the Full Conversation
Hear Alycia Wood’s full Jude 3 Project session on engaging atheism, where she works through this objection alongside several others skeptics commonly raise.
Alycia Wood is a Christian apologist and speaker who has appeared with the Jude 3 Project to address common objections to the Christian faith.