“Because of the evils and injustices that all war brings with it, we must do everything reasonably possible to avoid it. The Church prays: ‘From famine, pestilence, and war, O Lord, deliver us’.”
—CCC 2327

The Catechism of the Catholic Church begins its section on war with this solemn disclaimer, “The fifth commandment forbids the intentional destruction of human life. Because of the evils and injustices that accompany all war, the Church insistently urges everyone to prayer and to action so that the divine Goodness may free us from the ancient bondage of war.”  Pope John Paul II, who survived World War II and whose pontificate had to endure wars involving millions of Catholics made this exasperated plea in Centissiums Anus:

A Roman Catholic priest celebrates Mass during wartime.

Never again war! No, never again war, which destroys the lives of innocent people, teaches how to kill, throws into upheaval even the lives of those who do the killing and leaves behind a trail of resentment and hatred, thus making it all the more difficult to find a just solution of the very problems which provoked the war. (52)

As much as war can be glorified in movies and videogames, any veteran of combat can summarize their experience in this oft repeated phrase, “war is hell”. But while war always involves evils that will occur in combat, sometimes the choice to not engage in war can be an even greater evil.  This is the theory behind the Church’s teaching of the possibility that a nation can wage a just war. Based on the writings of St. Augustine, Catholic Just War theory requires in order for a war to be just, four conditions must be met:

• The damage inflicted by the aggressor on the nation or community of nations must be lasting, grave, and certain;
• All other means of putting an end to it must have been shown to be impractical or ineffective;
• There must be serious prospects of success;
• The use of arms must not produce evils and disorders graver than the evil to be eliminated. The power of modem means of destruction weighs very heavily in evaluating this condition. (2309)

In other words, only wars that are fought defensively against a grave evil, and are fought because all other peaceful options to resolve conflict have failed, and have a reasonable chance of victory without the use of evils that are worse than the evil being fought, can be considered just or moral.

Q: Can a Catholic serve in the military?

A: Yes, in fact the Church calls all people to be good citizens that serve lawful governments. However, a Catholic that serves as a member of the armed forces must discern the morality of any conflict they are involved in fighting. If a Catholic is ordered to commit an intrinsically evil act, such as the direct and intended killing of an unarmed civilian or the torture of a prisoner of war, then he or she must refuse to follow that order, even if such an order is legal in the soldier’s home country and would result in punishment as a result of disobedience. The catechism says, “Non-combatants, wounded soldiers, and prisoners must be respected and treated humanely. Actions deliberately contrary to the law of nations and to its universal principles are crimes, as are the orders that command such actions. Blind obedience does not suffice to excuse those who carry them out.” (CCC 2313)

“He shall judge between the nations, and set terms for many peoples. They shall beat their swords into plowshares and their spears into pruning hooks; One nation shall not raise the sword against another, nor shall they train for war again.”
—Isaiah 2:4