Open Historians agree religion is rarely the only cause of a war. How much it adds, and whether it calms or inflames conflict overall, is still debated.
“Religion has caused more wars than anything else.” You have probably heard it said, at school or over a family dinner. It sounds obvious. Most people who study war for a living think it is wrong, or at least far too simple.
But the opposite slogan, “religion is only ever about peace”, is not true either. So here, honestly, is the record of Judaism, Christianity and Islam: the wars fought in God’s name, and the believers who risked everything to stop them. People without religion have a record too, and they speak for themselves below.
“For that cause We decreed for the Children of Israel that whosoever killeth a human being for other than manslaughter or corruption in the earth, it shall be as if he had killed all mankind, and whoso saveth the life of one, it shall be as if he had saved the life of all mankind.”
Qur'an 5:32 · Pickthall (1930)
This verse follows the Qur’an’s story of Cain and Abel, and it says this teaching was given first to the Children of Israel. The Mishnah, written down around 200 CE, has the same teaching: whoever destroys a single soul is as if they destroyed a whole world, and whoever saves one is as if they saved a whole world (Sanhedrin 4:5). The verse names exceptions, for murder and for violent corruption; it does not forbid all force.
What historians and researchers find
Counting wars is harder than it sounds. The Encyclopedia of Wars, edited by Charles Phillips and Alan Axelrod (2004), lists 1,763 conflicts and classes 123 of them, about 7 per cent, as mainly religious. That figure is often quoted, but it counts entries, not deaths, and historians argue about how to label wars with many causes.
A more careful study came from the Institute for Economics and Peace in 2014. It looked at the 35 armed conflicts in the world in 2013. Religion played a part in 21 of them, but in none was religion the only cause. Most also involved disputes over territory, government, identity or resources.
Some wars really were fought in God’s name. The Crusades (1095–1291) were called by popes and fought by Christian armies. The Thirty Years’ War (1618–1648), which began partly as a struggle between Catholic and Protestant states, killed several million people in central Europe. But the deadliest conflicts of the twentieth century, the two World Wars, were not wars of religion, and some of the largest death tolls came from regimes that were officially atheist.
Scholars interpret this in different ways. William Cavanaugh, in The Myth of Religious Violence (2009), argues that the line between ‘religious’ and ‘secular’ violence is hard to draw at all. Rabbi Jonathan Sacks, in Not in God’s Name (2015), argued that religion turns dangerous when it fuses with group identity and a hunger for power, and people come to believe they are doing evil for good.
Research also shows that the influence runs both ways. A 2019 study by Joseph Henrich and colleagues of 1,709 people in Uganda, Sierra Leone and Tajikistan found that those who had suffered more in past wars were more likely, years later, to take part in Christian or Muslim religious groups and rituals. War makes people more religious, as well as the other way round.
The arguments, fairly
Absolute reasons. Christopher Hitchens and Sam Harris argued that religion gives people reasons to fight that cannot be questioned or bargained over, because they come from God. A land dispute can be split; a holy place, they say, cannot.
The hardest texts. Each scripture contains passages about war and enemies. Sceptics argue that however carefully scholars interpret them, these texts have been used to justify killing, and will be again.
Us and them. Religion binds communities together, which is part of its strength. Critics argue that the same bond draws a line against outsiders, and makes it easier to see them as enemies of God.
Religion is rarely alone. The 2014 study of 35 conflicts found no war caused by religion alone. Karen Armstrong, in Fields of Blood (2014), argues that most so-called religious wars were driven by states, land and power, with religion used as a banner.
Violence betrays faith. Rabbi Jonathan Sacks argued in Not in God’s Name (2015) that killing in God’s name is a betrayal of religion. He saw it as driven by group identity and rivalry, and traced it back to the sibling stories of Genesis. He argued that the same scriptures, read closely, teach the cure.
Secular ideologies killed too. The twentieth century’s wars and purges show that nationalism and atheist ideologies can be just as deadly. Removing religion does not remove the human appetite for conflict.
Religion also makes peace. Faith communities have led some of history’s great movements against violence, and religious teaching created many of the rules that limit war, from protecting civilians to honouring treaties.
Where it stands
Open. Most historians agree that ‘religion causes most wars’ is not supported by the evidence, and that religion is almost never the sole cause. Whether it makes conflicts worse when it is involved, longer, harder to end, more brutal, is still researched and debated.
No tradition, and no lack of tradition, has clean hands. Every one also has its peacemakers.
What each faith says
Judaism
“And they shall beat their swords into plowshares, And their spears into pruninghooks; Nation shall not lift up sword against nation, Neither shall they learn war any more.”
Isaiah 2:4 · JPS 1917
The Hebrew Bible does not hide war. The book of Joshua tells of the conquest of Canaan under Joshua, including commands to destroy whole cities, some of the hardest passages in scripture. Jews later fought the Seleucid Greeks (the Maccabees, 167 BCE) and rose twice against Rome. The rabbis, though, narrowed the conquest commands almost to nothing. The Mishnah taught that the ancient nations had long since been mixed together, and Maimonides ruled that peace must be offered before any war (Laws of Kings 6:1). For most of the last two thousand years Jews had no army at all, and were more often victims than fighters.
The prophet Isaiah gave the world its most famous vision of peace, quoted on the wall opposite the United Nations in New York. Hillel taught: “Be of the disciples of Aaron, loving peace and pursuing peace” (Pirkei Avot 1:12). The Talmud says that Shalom, peace, is one of the names of God.
Christianity
“Blessed are the peacemakers, for they shall be called children of God.”
Matthew 5:9 · WEB
Jesus taught his followers to love their enemies, and for nearly three centuries many Christians refused to serve as soldiers. After the Roman empire became Christian, Augustine developed the idea of a ‘just war’: fighting only for a just cause, by rightful authority, as a last resort. Then came the Crusades, in which Christian armies killed Jews in the Rhineland, Muslims and Jews in Jerusalem in 1099, and fellow Christians in Constantinople in 1204. Europe’s wars of religion set Catholics against Protestants for over a century.
The peacemakers are part of the record too. In the tenth and eleventh centuries, the church’s ‘Peace of God’ movement tried to protect peasants, clergy and the poor from knights. In 1219, during a crusade, Francis of Assisi crossed the battle lines in Egypt to speak with Sultan al-Kamil, who received him with courtesy. Quakers declared their refusal to fight in 1660, and Martin Luther King Jr drew his nonviolence from the Sermon on the Mount.
Christian peace work continues in many traditions. The Corrymeela Community in Northern Ireland, founded in 1965, brought Catholics and Protestants together through the Troubles. Coventry Cathedral, rebuilt beside its bombed ruins, leads a worldwide Community of the Cross of Nails, and still prays the Litany of Reconciliation every weekday at noon: “Father, forgive.”
Islam
“And if they incline to peace, incline thou also to it, and trust in Allah. Lo! He, even He, is the Hearer, the Knower.”
Qur'an 8:61 · Pickthall (1930)
Islam began in a world of war, and the Prophet Muhammad ﷺ (peace be upon him) led his community in battles. Within a century of his death, Arab armies had conquered lands from Spain to Central Asia. Muslims also fought one another, from the first civil war and the Battle of Siffin in 657 onwards. In recent times, armed groups have claimed Islam to justify terrorism; the overwhelming majority of Muslim scholars have condemned them.
The tradition also set strict limits. The Qur’an says, “Fight in the way of Allah against those who fight against you, but begin not hostilities. Lo! Allah loveth not aggressors.” (2:190, Pickthall). The Prophet forbade the killing of women and children (Bukhari 3015), and the first caliph, Abu Bakr, is reported to have told his army not to kill the old, cut down fruit trees or harm monks in their cells (Muwatta Malik 21:10). The Prophet made peace at Hudaybiyyah in 628 on terms his companions disliked. When Saladin retook Jerusalem in 1187 there was no massacre; its people were allowed to ransom themselves. In 1860 the Algerian scholar Emir Abdelkader sheltered thousands of Christians in Damascus during a massacre, and in the 1930s the Pashtun Muslim Abdul Ghaffar Khan led a nonviolent army of tens of thousands.
Without religion
“Roughly speaking, the word humanist has come to mean someone who … makes their ethical decisions based on reason, empathy, and a concern for human beings and other sentient animals”
Humanists UK, ‘What is humanism?’ · original English
Non-religious people bring both a criticism and a confession to this question. The criticism is the one Christopher Hitchens made in God Is Not Great (2007): that faith gives people reasons to fight that cannot be bargained over. The confession is that twentieth-century atheist regimes, in the Soviet Union, China and Cambodia, killed millions. Many humanists say plainly that no worldview, their own included, is immune to cruelty.
Non-religious people have their peacemakers too. In 1955 Bertrand Russell, with Albert Einstein, issued the Russell–Einstein Manifesto against nuclear war, and in 1958 Russell became the first president of the Campaign for Nuclear Disarmament. The psychologist Steven Pinker argues in The Better Angels of Our Nature (2011) that violence has fallen over the centuries, and credits reason and humanist values.
Same and different
Judaism, Christianity and Islam have each fought wars in God’s name, and each has scriptures and teachers that limit war and honour peacemakers. They share the teaching that one life is worth a whole world, found in both the Mishnah and the Qur’an. They differ in history: early Christianity was largely pacifist and later developed just-war rules; Judaism had a biblical history of war and then two thousand years without an army; Islam had rules of war from its earliest days. Other traditions, and secular and atheist regimes, have their own wars; people of every tradition and none have their peacemakers.
A moment to reflect
- When someone says ‘religion causes war’, what do you think they really mean? What would change their mind?
- Can a faith be judged by its worst moments, or by its best, or neither?
- Which story of a peacemaker on this page surprised you most, and why?
- Is there anything you hold so dear that you might be tempted to fight for it? How would you keep it from turning into hatred?
We end on a question
If every tradition, religious or not, has both warriors and peacemakers, what decides which one a community becomes?
Watch
A clear introduction to just war theory, the rules many traditions use to limit fighting.
Rabbi Jonathan Sacks’s Templeton Prize lecture on confronting violence done in God’s name.
The Cambridge scholar Timothy Winter (Abdal Hakim Murad) on the ethics of war in Islamic teaching.
Religious studies scholar Andrew Henry explains the research showing that war makes people more religious.
Do it together
Each person researches one peacemaker of any faith or none, such as Francis of Assisi, Emir Abdelkader or Martin Luther King Jr, and makes a poster. Display them together: what did they share?
Read Mishnah Sanhedrin 4:5 and Qur’an 5:32 side by side. Discuss why two scriptures share the same teaching, and how it might shape the way we speak about people we disagree with.
Visit a local war memorial together, ideally around Remembrance Sunday. Look for the names, and the faiths, of those listed. Share a minute’s silence and a short reading for peace from each tradition present.
Mitzvah Day, started by the UK Jewish community in 2008, is a day of social action each November that welcomes people of every faith and none. Join or start a project together, such as a food collection or a litter pick, and work side by side.
Read Coventry Cathedral’s Litany of Reconciliation. Each line names a human failing and answers “Father, forgive.” Then write a line of your own about a division in your own town.
Go deeper
- Five Key Questions Answered on the Link between Peace and Religion (IEP, 2014) · paper
- War (Stanford Encyclopedia of Philosophy) · article
- Mishnah Sanhedrin 4:5 (Sefaria) · scripture
- Qur'an 5:27–32 (Quran.com) · scripture
- Matthew 5 (Bible Gateway, WEB) · scripture
- Religion, peace and conflict, GCSE RS (BBC Bitesize) · article
- Rabbi Jonathan Sacks, Not in God’s Name (rabbisacks.org) · book
- Mitzvah Day · article
Check yourself
Three quick questions. No score, nothing saved.
1. One count on this page classes about how many recorded wars as mainly religious?
2. In 2013, how many of 35 armed conflicts had religion as their only cause?
3. Qur'an 5:32 says that whoever saves one life is as if they had saved…
Sources (10)
- Encyclopedia of Wars: 123 of 1,763 conflicts classed as religious; figure contested: Religious war (Wikipedia summary of Phillips and Axelrod 2004)
- 35 conflicts in 2013; religion in 21; never the sole cause: Institute for Economics and Peace, Peace and Religion report, 2014
- War increases religiosity: 1,709 people in Uganda, Sierra Leone and Tajikistan: Henrich et al., Nature Human Behaviour 3, 2019
- Thirty Years' War, 1618–1648: Britannica, Thirty Years' War
- Crusades, 1095–1291; Jerusalem 1099; Constantinople 1204: Britannica, Crusades
- Francis of Assisi meets Sultan al-Kamil, 1219: Britannica, Saint Francis of Assisi
- Emir Abdelkader protects Christians in Damascus, 1860: Britannica, Abdelkader
- Abdul Ghaffar Khan and the nonviolent Khudai Khidmatgar: Britannica, Abdul Ghaffar Khan
- Abu Bakr's instructions to the army: Muwatta Malik 21:10, Sunnah.com
- Prophet forbade killing women and children: Sahih al-Bukhari 3015, Sunnah.com
