War: Just War, Holy War & Pacifism
Reasons for War
War is an armed conflict between two or more sides, usually nations or organised groups. There are many reasons why wars begin, but the three main reasons studied in GCSE Religious Studies are greed, self-defence and retaliation.
Greed drives wars fought for power, territory or resources. Many governments disguise greed as other motivations, but religious believers generally consider greed an unjust reason for war. Self-defence is widely accepted as a legitimate reason for fighting — both Christians and Muslims agree that protecting yourself and others from harm is justified. Retaliation means fighting back as revenge for a previous attack. While it can deter future aggression, religious believers warn that retaliation often creates a cycle of violence.
Just War Theory
The just war theory draws on the work of St Thomas Aquinas, who in the 13th century (Summa Theologiae II-II Q40) gave three conditions: just cause, right intention, and legitimate authority. Later Christian teaching added more conditions. The Catholic Catechism of 1992 says that war must be a last resort, must have a serious chance of success, and must not cause greater harm than it prevents. Church teaching also forbids the deliberate killing of civilians. It recognises that while peace is always preferable, there are circumstances where war may be the lesser evil.
The criteria for a just war include: (1) it must be fought for a just cause, such as self-defence; (2) it must be declared by a legitimate authority, such as a government; (3) the intention must be to promote good and overcome evil; (4) war must be a last resort, after all peaceful alternatives have been exhausted; (5) there must be a reasonable chance of success; (6) proportional force must be used — no more violence than is necessary; (7) civilians must not be deliberately targeted.
Most mainstream Christian denominations accept the just war theory. The Catholic Church teaches that governments have a right and duty to defend their citizens, provided the strict conditions of a just war are met. The Church of England also supports the just war approach, arguing that there are times when failing to act would cause greater suffering.
However, Jesus’s own teaching emphasises peace and non-violence. He said: “Love your enemies and pray for those who persecute you” (Matthew 5:44) and “All who draw the sword will die by the sword” (Matthew 26:52). This creates a tension within Christianity between the ideal of peace and the practical reality that war may sometimes be necessary.
Holy War
A holy war is a war fought for a religious cause or believed to be commanded by God. In Christianity, the Crusades (11th–13th centuries) are the most well-known example — European Christians fought to recapture the Holy Land from Muslim control. In Islam, the concept of lesser jihad permits armed struggle to defend Islam, but only under strict conditions.
For a holy war to be legitimate in Islam, it must be declared by a recognised religious authority, be fought in self-defence (not aggression), use proportionate force, and not target civilians, the elderly, women or children. The Qur’an states: “Fight in the way of God those who fight you, but do not transgress. Indeed, God does not like transgressors” (2:190).
Just war vs holy war: A just war uses moral criteria to decide if a war is acceptable — it does not have to be religious. A holy war is fought specifically for a religious cause. Today, most Christian and Muslim leaders reject the idea of holy war, arguing that religion should not be used to justify violence.
Pacifism
Pacifism is the belief that all violence and war is wrong, regardless of the circumstances. Pacifists argue that conflicts should always be resolved through dialogue, negotiation and peaceful protest.
The strongest pacifist tradition in Christianity comes from the Quakers (Society of Friends), who believe that all war is wrong. They follow Jesus’s teaching to “turn the other cheek” (Matthew 5:39) literally and refuse to fight in any conflict. Many Quakers served as conscientious objectors during the World Wars, working as ambulance drivers or in hospitals instead.
Islam does not have a strong pacifist tradition in the same way. The Qur’an permits self-defence, and Muhammad himself participated in battles to protect the early Muslim community. However, many Muslims point out that the word Islam comes from the same root as salaam, meaning peace, and that the greater jihad — the internal struggle to be a good Muslim — is more important than any physical conflict.
Religion as a Cause of War
Religion has been cited as a cause of conflict throughout history — from the Crusades to modern-day conflicts in the Middle East. However, many scholars argue that religion is rarely the sole cause of war. Most conflicts involve a complex mix of political, economic and territorial factors, with religion sometimes used to justify violence rather than being its root cause.
Both Christians and Muslims argue that their faith promotes peace, not war. Where religious violence occurs, leaders from both traditions condemn it. Pope John Paul II declared in 2003 that “war is always a defeat for humanity,” a line Pope Francis has repeated, and Muslim scholars worldwide have signed declarations condemning violence carried out in the name of Islam.
Christianity: Quakers take an absolute pacifist position, rejecting all violence. Most other Christian denominations accept that war may sometimes be necessary (just war theory) but should always be a last resort. All Christians agree that Jesus taught peace and non-violence as the ideal.
Islam: Most Muslims are not pacifists in the absolute sense. The Qur’an permits self-defence, and Muhammad fought to protect the Muslim community. However, peace is the preferred state, and the greater jihad (inner spiritual struggle) is considered more important than the lesser jihad (armed conflict). Some individual Muslims, such as Abdul Ghaffar Khan, have adopted pacifist positions inspired by their faith.