What Scripture says
Jesus taught his followers to love their enemies and pray for those who persecute them (Matthew 5:44, ESV). When Peter drew a sword to defend him, Jesus said, “Put your sword back into its place. For all who take the sword will perish by the sword” (Matthew 26:52). He said, “My kingdom is not of this world. If my kingdom were of this world, my servants would have been fighting” (John 18:36). Paul wrote, “the weapons of our warfare are not of the flesh” (2 Corinthians 10:4), and “Repay no one evil for evil” (Romans 12:17).
What the evidence says
History
How many wars were religious?
Phillips and Axelrod’s Encyclopedia of Wars (2004) catalogues 1,763 wars across recorded history. It classifies 123 of them, about 7%, as primarily religious. Most wars have been about land, resources, power, nationalism or ideology.
Scholars caution that “religious war” is hard to define: religion is often mixed with ethnic, political and economic motives. William Cavanaugh argues that the idea of religion as uniquely violent is itself a modern myth, used to favour secular states.
The 20th century
The deadliest century in history was dominated by secular and anti-religious regimes:
| Conflict or regime | Approximate deaths | Ideology |
|---|---|---|
| World War II | 70–85 million | Nationalism, fascism |
| Mao’s China | 40–70 million | Atheistic communism |
| Stalin’s USSR | 6–20 million | Atheistic communism |
| Khmer Rouge, Cambodia | 1.5–2 million | Atheistic communism |
This doesn’t prove atheism causes violence, but it shows that removing religion doesn’t remove war.
The Crusades
The Crusades (1095–1291) were a series of wars, launched by popes, to recover Jerusalem and the Holy Land from Muslim rule. They should be owned honestly:
- Crusaders massacred Muslims and Jews when they took Jerusalem in 1099.
- Crusaders attacked Jewish communities in Europe on their way east.
- The Fourth Crusade sacked Christian Constantinople in 1204.
Context matters but doesn’t excuse: the Crusades responded to centuries of Islamic expansion into once-Christian lands, and to an appeal for help from the Byzantine emperor. Historians such as Thomas Madden and Rodney Stark argue they were defensive in origin, though they quickly involved greed and brutality.
The Inquisition
The Spanish Inquisition (1478–1834) investigated people suspected of heresy, especially Jewish and Muslim converts. Historians now estimate around 3,000–5,000 executions over three and a half centuries, far fewer than once claimed, but still a grave wrong. Its use of torture and its targeting of converts contradicted the gospel it claimed to defend.
Wars of religion
The European wars of religion (16th–17th centuries), including the Thirty Years’ War (1618–48), pitted Catholics against Protestants, though political rivalries between states were also central: Catholic France fought on the Protestant side.
Scripture
These events contradict Jesus’ teaching rather than follow it. Christians who committed violence in Christ’s name acted against his commands (Matthew 5:44, 26:52). At the same time, Christian faith motivated hospitals, the abolition of slavery (see 9.6), care for the poor and peacemaking movements.
Where they meet
Most wars aren’t mainly religious. The Crusades and the Inquisition happened and should be owned honestly, but they contradict Jesus’ teaching rather than follow it.
What’s still open
How to define a “religious” war, and how much religion contributed to specific conflicts.
Bottom line
Most wars aren’t mainly religious. The Crusades and Inquisition happened and should be owned honestly, but they contradict Jesus’ teaching rather than follow it. This is rated Debated.