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On Feb. 28, the United States, in coordination with Israel, launched a bombing campaign against Iran, kicking off a series of debates about the justification for war. Secretary of Defense Pete Hegseth asserted that, in this conflict against a Muslim-majority nation, God was on the American side and that everyone in the nation should be praying for victory in battle “every day on bended knee with your family, in your schools, in your churches, in the name of Jesus Christ.”
Others in the administration offered similar comments, including President Donald Trump, who promised on April 7 that “a whole civilization [would] die tonight” if Iran failed to meet U.S. demands. Pope Leo XIV soon after spoke out against violence, though he did not name the president or the war itself.
“Anyone who is a disciple of Christ, the Prince of Peace, is never on the side of those who once wielded the sword and today drop bombs,” the Catholic pontiff said. This resulted in a widely reported debate among pundits, leaders and others about whether the war was just or appropriate. Lost in the conversation, though, was the actual meaning of the phrase “just war.”
“Just war was never about easing our consciences about war,” said Ryan Cumming, director for theological ethics at the ELCA churchwide office. “It’s about wrestling with challenging questions of justice and having a language for talking about when war is justified and when it is not.”
The Christian concept of a just war is often claimed to originate with fourth-century theologian Augustine of Hippo, though his inspiration came from both Christian and non-Christian thinkers, such as Cicero and Ambrose. His work focused on the fate of the Roman Empire amid large-scale internal and external conflicts.
Augustine viewed war as a tragic exception, a necessary evil. Conflict was not a means to an end but rather something that must be waged in love, particularly the love of the enemy. The other component of Augustine’s views on war surrounded the reality that no war could result in perfect peace. In other words, he saw that justice demands that political rulers avoid war unless it is necessary to stop a clear, unavoidable threat. But even then, the objective was not to destroy an enemy but to end the conflict.
One of the valuable insights from Augustine, according to Cumming, is the tension of discerning justice in an imperfect world. “Augustine’s thought on war is about this tension between government’s duty to oppose the chaotic forces of injustice with the aim of promoting a just peace and a sense of humility that recognizes that no peace brokered by human efforts can grant permanent security and true justice,” Cumming said.
For centuries after Augustine, writers amended the theory, changing what makes a war justified, who has the authority to declare war, what makes a cause worthy of violence, and how evil should be determined. But where they continued to agree was that wars waged in the name of God or religion were unjust.
“Holy war has never been acceptable in ‘just war’ theory,” Cumming said. “When we start believing God is on our side, or we are fighting in the name of Christ, we have moved completely away from the history of ‘just war’ theory.”
The significant changes in the theory that led to the modern version occurred in two distinct eras. First, Thomas Aquinas wrote that political leaders could lose their legitimacy when they acted in their own interests rather than for the common good. Later, Spanish theologian Francisco de Vitoria took Aquinas’ argument a step further, arguing that leaving war to the decision of a political authority alone could lead to poor decisions, especially since rulers were more likely to act out of greed or selfishness. Another Spanish theologian, Francisco Suárez, agreed, arguing that public counsel should guide decisions about war.
“Suárez and Vitoria were responding to real atrocities,” Cumming said. “They insisted that rulers don’t get to declare war simply because they can.”
Early Lutherans did not deviate from the tradition of just war but instead embraced it. Article XVI of the Augsburg Confession affirms that civil authority can be a legitimate calling and civil authorities can appropriately wage just wars, though this has often been misinterpreted as requiring uncritical obedience and support for the war-waging authority of government. Martin Luther was especially critical of political authorities regarding war.
“It is not right to start a war just because some silly lord has gotten the idea into his head,” Luther wrote.
After the 1600s, just war theory didn’t experience much significant development.
“For a long time, ‘just war’ functioned as background moral consensus,” Cumming said. “It wasn’t examined deeply. It was assumed.”
That assumption fractured in the 20th century amid two world wars, the use of chemical weapons in the first and atomic weapons in the second, and the reasoning behind both conflicts, as well as the Holocaust. Christians were now forced to consider the frameworks that defined what constituted a just war. World War I led to a shift in the discussion, from whether a war should start, to questions about how it should be waged, how to treat civilians caught in the crossfire, and whether a military response is proportionate to the original attack.
Adding to the conversation were the ideas of “military actions” that fell outside the standard definition of war, humanitarian interventions such as the NATO bombing during the Kosovo War in 1999, and, now, “preventative wars.”
The ELCA’s 1995 social statement, “For Peace in God’s World,” affirms just war theory as a moral framework and urges governments to “vigorously pursue less coercive measures over more coercive ones: consent over compulsion, nonviolence over violence, diplomacy over military engagement, and deterrence over war.”
Lutheran ethicists have increasingly emphasized that “just war” theory is primarily a call to peacemaking rather than a quick way to justify violence. Writing in the Journal of Lutheran Ethics (JLE), ethicists argue that political power exists to serve peace. Any moral analysis must extend beyond battlefield decisions to the social, political and economic dynamics that led to war in the first place.
Others have called for revising the vocabulary behind “just war” theory altogether. In the JLE essay “A New Language for Just War,” Wollom A. Jensen argues that traditional moral frameworks for war are often too narrow to address modern warfare or the spiritual wounds it leaves behind. He urges the church to speak honestly not only about justification but about trauma, moral injury and the repercussions of violence.
For Cumming, the most faithful role of just war theory is not to provide certainty but to cultivate humility.
“The decision to go to war should always be a mournful one. There are times when we have to wage war, but we never enter it with triumphalism. We enter it, wage it, and end it with grief and mourning.”
This story was updated to reflect the version that appeared in print.
