What does the church teach about self-defense?

If protecting innocent life were the single highest moral value, then using violence to protect lives would be morally acceptable, but other Christian values complicate this moral calculation.

With nearly one-third of Americans owning a firearm, the United States ranks first in per capita gun ownership. According to Pew Research, protection is the most common reason for gun ownership. But is protection justification for owning a deadly weapon? And under what circumstances might violent self-defense be justified?

Today, the Catholic Church recognizes human dignity as a fundamental moral value and holds that directly causing the death of an innocent person is always wrong. In contrast, someone who intends to harm another person is, by definition, non-innocent. An attacker’s life does not enjoy comprehensive moral protection. If protecting innocent life were the single highest moral value, then using violence to protect lives would be morally acceptable and perhaps even morally required. However, other Christian values complicate this moral calculation.

Early Christians were not prone to thinking about self-defense as a moral dilemma. Their writings overwhelmingly oppose killing, full stop. Violent self-defense was simply indefensible. Forcefully resisting an attack involves violence and suggests that one values their own life above that of their neighbor (albeit an aggressive neighbor). Christ did not resist arrest, beating, or death, so why should his followers? The early Christians’ embrace of martyrdom can startle modern readers, but such was their confidence in eternal life with Christ as their highest good.

As time went on, Christianity gained social and political power and wrestled more profoundly with the relationship between faith and violence. While both personal and political pacifism remained options, Christianity increasingly accepted the use of force as a possible moral necessity. Thomas Aquinas acknowledged the value of the natural instinct to preserve one’s own life. He judged using necessary violence against an attacker morally justifiable, provided defense was truly the underlying motive.


Aquinas’ qualification stems from a moral insight now known as the “principle of double effect.” This principle observes that single actions can have multiple outcomes. In the case of violent self-defense, these include harming an aggressor and defending innocent life. With lives at stake either way, the morality of the action comes down partially to intention. It is never right to kill when killing is the direct and intended outcome. However, if the act of protecting life also entails the taking of life as an unintended secondary effect, there are times when this may be justifiable.

Today, the church continues to utilize this line of reasoning in teaching that a Catholic may legitimately use deadly force to defend one’s own life or the lives of others. Yet Christians remain called to be peacemakers. Consequently, a Catholic may choose to permit or endure violence. Doing so could witness to the inherent value of all human life. Whatever the case, Christians are always called to uphold inherent human dignity. 

This article also appears in the June 2024 issue of U.S. Catholic (Vol. 89, No. 6, page 49). Click here to subscribe to the magazine.

Image: Unsplash/Nathan Dumlao

About the author

Jacob Kohlhaas

Jacob Kohlhaas is an assistant professor of moral theology at Loras College in Dubuque, Iowa.

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