The Basics of Just War Theory

When you read the Bible you see clearly that God is not anti-war.  War was not part of God’s original plan in creating mankind, but because of sin, war is necessary at times. 

In fact, on multiple occasions God commanded the Jews to wage war. 

• Deuteronomy 20:17 (CSB) says, “You must completely destroy them—the Hethite, Amorite, Canaanite, Perizzite, Hivite, and Jebusite—as the Lord your God has commanded you.”  
• 1 Sam 15:3 (CSB) says, “Now go and attack the Amalekites and completely destroy everything they have. Do not spare them. Kill men and women, infants and nursing babies, oxen and sheep, camels and donkeys.’”

It is important to note that not all wars are just; and not all forms of waging war are just.  Over the centuries Christians have developed an ethic for warfare called Just War Theory.  The idea is that war is sometimes necessary and permissible, but only under the following conditions: 

1) Just cause:  Is the reason for going to war a morally right cause, such as defense of a nation? 

2) Competent authority:  has the war been declared not simply by a renegade band within a nation but by a recognized, competent authority within the nation? 

3) Comparative justice:  It should be clear that the actions of the enemy are morally wrong, and the motives and actions of one’s nation in going to war are, in comparison, morally right. 

4) Right intention:  Is the purpose of going to war to protect justice and righteousness rather than simply to rob and pillage and destroy another nation? 

5) Last resort:  Have all other reasonable means of resolving the conflict been exhausted? 

6) Probability of success:  Is there a reasonable expectation that the war can be won? 

7) Proportionality of projected results:  Will the good results that come from a victory in a war be significantly greater than the harm and loss that will inevitably come with pursuing the war? 

8) Right spirit:  Is the war undertaken with great reluctance and sorrow at the harm that will come rather than simply with a delight in war? 

As well, the Just War Theory defines guidelines for how war should be fought. 

1) Proportionality in the use of force:  No greater destruction should be caused than is needed to win the war. 

2) Discrimination between combatants and noncombatants:  Insofar as it is feasible in the successful pursuit of a war, is adequate care being taken to prevent harm to noncombatants? 

3) Avoidance of evil means:  Will captured or defeated enemies be treated with justice and compassion, and are one’s own soldiers being treated justly in captivity? 

4) Good faith:  Is there a genuine desire for restoration of peace and eventually living in harmony with the attacking nation?

(Source:  ESV Study Bible, p. 2555)