Just War: Considerations for Christians

First in a Series of Reflections: Introduction to Just War

By Dana Grubb

Hundreds of years before the Christian era, several ancient societies (e.g., Egypt and India) considered what conditions should exist before a nation should enter a war and what limitations were needed on waging a war. 

Early Christians were for a long time barred from joining the Roman Army. This was due in large part to pagan observances in the Army and the Church’s banning Christian participation in pagan rites. Jesus’ proclamation to his followers that they should love their enemies and his telling Peter to put away his sword may also have been factors. 

However, by about year 180 CE some Christians were enlisting in the Army and larger numbers did so in following years. By the late fourth century, there were many Christians serving in the Roman Army. This raised the question whether Christians should participate in war and, if so, were there wars that they should refuse to participate in. (The Roman Army was noted for its brutality, including the slaughter of all the civilians and their children in conquered cities.)

The Christian concept of a Just War evolved from the writings of St. Augustine, Bishop of Hippo, around the year 400. In the 13th century, Thomas Aquinas developed three specific criteria: It must be waged by a lawful government; waged for a just cause; and waged with a right intention. 

Through the centuries, Roman Catholic and secular scholars have greatly expanded and developed the criteria for determining if a war may be considered to be a Just War. The lists of criteria vary somewhat, even among Roman Catholic scholars. We have selected some of the most commonly used criteria for this paper, plus a few proposed End of War criteria by modern scholars. 

Phases of a Just War

The Just War theory is usually divided into phases: Cause, Conduct and, perhaps, Ending a war. 

1] Just Cause for a war is traditionally sub-divided into two situations:

  a] An armed attack on a peaceful nation or one of their allies has occurred. The attack itself is considered to be a justification for going to war with the aggressor. (Skip to "Just Conduct Criteria.")

  b] Other types of armed actions require that several criteria must all be met to initiate a just war.

2. Just Conduct in the waging of a war. Regardless of the cause for a war, several criteria all must be met for the conduct of the war to be considered just.

3. Just Ending for a war is needed to repair harm done by the war.

The Just War Criteria

Just Cause Criteria: 

1] Legitimate AuthorityA national government or similar authority (e.g., the United Nations Security Council). An internal revolution would not qualify.

2] Just CauseThe war must be against a serious public wrong. For example, a war to stop the genocide of Jews in another country would qualify. A war to annex land in another country would not qualify.

3] Right IntentionLeaders must be motivated by a national goal that makes the war just, and not by some illegitimate motive, such as annexing land or installing a puppet regime.

4] Proportionality: The war must be reasonably expected to do more good than harm. Given the great damage done in most wars, the harm done by not going to war must be very great. 

5] Probability of SuccessThe war must have a reasonable chance for victory. This could be problematic in some cases. For example, even with a much stronger military, the U.S. could not defeat North Vietnam; even the mighty British Army could not defeat George Washington's small volunteer army. 

6] Last ResortWar must not be used until the other options, such as negotiation, diplomatic pressure, etc. have been ineffective or impractical. (Economic sanctions can cause great harm to the public if it depends on imports for fuel or heat, etc. However if a rapidly moving genocide or ethnic cleansing is in progress, a drawn out use of other options would be of no value.

Just Conduct Criteria:  

Discrimination: Military forces must not attack non-combatants. Bombing of entire cities, towns or residential areas is forbidden. Civilian areas that have some enemy assets must not be attacked with weapons of mass destruction or the use of unguided missiles. The World War II massive bombings of London, Dresden, Tokyo, Nagasaki and Hiroshima violated this criterion, as do Israeli bombings of schools, hospitals, sewage treatment facilities, etc. in Gaza.

2] Proportionality: The harm done must not exceed the good sought. Ideally, the military force used would be capable of a relatively quick victory with minimum harm to civilians. A long, drawn out war will usually result in extensive collateral damage, with high casualties and vast property damage.

3] Military Necessity: A military attack must be focused entirely on defeating enemy forces. It must not have any other objective, such as killing off their children. Allegations that weapons are being hidden in a hospital does not justify bombing the hospital. 

4] Fair Treatment of Prisoners: Prisoners of war have basic human rights that must no be violated. These include housing, food, clean water, medical care, etc. There must be no waterboarding, sleep deprivation, solitary confinement or other type of torture.

5] No Evil Methods Used: There must be no use of biological weapons; no mass rape of women and girls, etc.

Just End of War Criteria:

1] Status of rights before war: The end of a war should be followed by a restoration of property rights and human rights as existed before the war.

2] Punishment for war crimes: Political leaders and military commanders on either side who were guilty of war crimes should be tried and punished for their crimes. The Nuremberg war crimes trials did this for German war criminals, but did not punish allied war criminals. 

3] Peace treatiesA peace treaty must be fair to both sides. No excessive war reparation penalties, as were applied to Germany after World War One.

4] Settlements: The military occupation of a nation must not involve the eviction of its residents from their homes or razing of their homes for the purpose of moving in settlers from the winning nation. Israel has done this in the Palestinian West Bank over a period of several decades and now has over 400,000 people living in Israeli settlements in Palestine.

5] Compensation for VictimsInnocent victims of the war should be compensated to the extent that it is possible to do so. Germany provided some compensation to Jewish families who lost family members due to the Nazi Holocaust during World War Two.

Current Factors Being Considered:

The effect of non-state groups (e.g., ISIS) and rapidly developing military technology. Examples of the latter include: inexpensive automated drones that can be used by minor powers, humans controlling weapons at very remote distances from their targets, and methods for destroying crops, poisoning water supplies, and damaging electric power grids.

The next Just War reflection: A Critique of the Just War 

While the Just War theory is a topic of interest to the military, there are numerous critics, who doubt that any contemporary war can be considered “just.” Some doubt that it ever was a valid theory.

For example: The good sought by contemporary wars, with their increasingly powerful weapons, compares poorly with the massive number of casualties caused by a war. 

For example: It is hard to reconcile Jesus’s teaching us to love our enemies with the waging war against our enemies. 

The next Reflection is titled “Critique of the Just War.” It considers these and several other problems with the Just War theory. Each of the Just War Criteria is examined per these problems. 


Morality and War, David Fisher, 2011. A very useful book on the Just War by a scholar who has served in senior positions at the British Ministry of Defense

 The Just War Tradition – An Introduction, David D. Corey and J. Daryl Charles, 2018. A good, useful book by secular scholars.

Wikipedia http://en.wikipedia.org/wiki/Just_war-theory

The Ethics Center https://ethics.org.au

Thinking Faith http://www.thinkingfaith.org/articles Catholic

2045 West Grand Ave, Suite B #40058, Chicago, IL 60612-1577 © 2020 EPF National. All rights reserved.
chevron-down linkedin facebook pinterest youtube rss twitter instagram facebook-blank rss-blank linkedin-blank pinterest youtube twitter instagram