Several winters ago, a few weeks before Christmas, I went to confession. The parish close to work was hosting a reconciliation service, meant to prepare the faithful to celebrate the birth of Christ. A dozen or so priests were scattered across the cathedral. Penitents lined the aisles. Whispers of contrition and pardon filled the air.

The Catholic Church counsels believers to seek confession regularly—at the very least, once a year. I hadn’t been back in a few. So in addition to feeling spiritually unmoored, I was worried about how the priest would react to hearing about my hiatus. But when I told him, he simply smiled and said, “Welcome back.” His response put me at ease then, and it helped change how I approach the sacrament now: less as a nerve-racking ordeal, more as a moment of mercy.

Sacraments such as confession are central to Catholicism. Through them, the Church teaches that simple actions—having a conversation with a priest, eating bread and drinking wine—are, with grace, tangible encounters with God. For the past year, the Trump administration has been making it harder for Catholics at migrant-detention centers to have those encounters.

The most recent example came to light this month, when the Archdiocese of St. Louis filed a federal lawsuit over the visitation policy at Saint Genevieve County Jail in eastern Missouri. According to the claim, the 10 priests who minister at the jail aren’t allowed to celebrate Mass. The suit also alleges that priests are permitted to visit migrant detainees just once a week, during a four-hour period, and that the jail’s “no contact” security policy lets the clergy speak with detainees only over the phone, through a glass partition. As a result, the approximately 150 migrants at the jail at a given time—most of whom are Catholic, according to the archdiocese—have been going without their religious needs for weeks. Since the middle of 2025, according to the lawsuit, Saint Genevieve has housed approximately 3,000 people.

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This isn’t the first time that Catholic clergy have complained that the government is preventing them from ministering to detained migrants. Last year, the Florida detention facility known as “Alligator Alcatraz” kept priests from visiting or offering Mass to detainees for a month, until an agreement was reached between the Archdiocese of Miami and state authorities. In May, after a six-month legal fight, a Catholic nonprofit won a preliminary injunction to let Catholic priests celebrate Mass and administer sacraments at the Broadview ICE processing center outside Chicago. And the administration’s immigration crackdowns seem to be hurting the Church more broadly. Dioceses across the country have reported decreased Mass attendance among Spanish-speaking parishioners who fear detention. ICE has reportedly conducted raids near Catholic churches during Mass hours.

The Department of Homeland Security has denied allegations of wrongdoing at Saint Genevieve. In a statement to multiple outlets, the agency said that the jail is not an ICE facility—although Saint Genevieve is listed as a detention facility on ICE’s website—and that it “ensures detainees are accommodated with religious services.” As described in the lawsuit, however, those accommodations disregard the religious significance of the Catholic sacraments.

Consider confession. The suit claims that at Saint Genevieve, conversations between detainees and priests are not private, and the phone lines that they use to talk may be monitored. These policies may be in place for security reasons, but confession is meant to be a private exchange between penitent and priest, who acts in persona Christi—in the person of Christ. Confession is “one of the most intimate, profound acts that someone can do,” David Inczauskis, a Jesuit priest who ministers at the Broadview ICE facility, told me. He added, “To state very specifically the sins that they have committed and to ask humbly for pardon and for peace” requires a “level of vulnerability” that is “very high.”

An even bigger problem comes up with the sacrament of the Eucharist, or Communion. The complaint includes an email from a deputy at the local sheriff’s office suggesting that priests “provide an unopened, individually wrapped Communion wafer” to a member of the detention center staff, who could then hand it to a detainee. This way of distributing the Eucharist would be “sacrilegious,” as Archbishop Mitchell Rozanski of St. Louis recently told Reuters. The Church teaches that the Eucharist is the “Body, Blood, Soul, and Divinity” of Christ—not a symbol, but God’s real presence. For that reason, Inczauskis said, the Church distributes the Eucharist through either ordained ministers or specially trained laypeople.

[Read: The Catholic Church and the Trump administration are not getting along]

For much of the past quarter century, many conservative figures have taken up religious liberty as an essential cause. The Trump administration purported to continue these efforts when it established a commission last year meant to identify “emerging threats” to the exercise of faith. In June, the commission released a draft report claiming that “in recent years, Americans from all religious backgrounds have faced increasing persecution for their religious beliefs.” Some of the issues discussed in the report include rising anti-Semitism, how gender and sexuality is taught in schools, and conscience protections for health-care workers who object to participating in abortions or assisted suicides. The report said nothing about the administration’s migrant-detention practices.

When the commission was announced, my colleague Elizabeth Bruenig wrote that “Christians shouldn’t conclude” that it would “necessarily defend their interests.” That warning seems prescient a year and a half later. At Alligator Alcatraz, Broadview, and Saint Genevieve, the Catholic Church has shown that it believes that detainee access to the sacraments matters deeply. Given the choice between restricting immigration and protecting the religious liberty of migrants, the administration, too, has demonstrated where its values lie.

Updated at 9:30 a.m. ET on October 17, 2026

When Pope Leo took heat from Donald Trump and the MAGA movement for denouncing the war in Iran earlier this year, much of his Church stood with him. Conservative and liberal Catholics alike argued that Leo was right to condemn the fighting, given the administration’s holy-war rhetoric and its inconsistent justifications of the conflict.

This broad agreement among Catholics, however, hid a more fundamental dispute—not about Trump or Iran, but about the principles that guide how the Church thinks about war. The “just war” theory, which draws from Saint Augustine’s writings during the fall of the Roman empire and was systematized in the Middle Ages by Saint Thomas Aquinas, exists to address a persistent theme in human history: Bad actors regularly commit terrible deeds, and nations must decide when and how to defend themselves, or to intervene on behalf of others. According to the framework, an armed conflict must have a just cause, such as responding to an unprovoked attack. It must be pursued as a last resort and have reasonable hope of success. It must be motivated by good intentions and carried out by a legitimate authority. It must rely only on just means, such as using proportional force and distinguishing between combatants and civilians. Its expected good must outweigh its inevitable harm.

Despite its long lineage, just-war theory’s influence in Catholic thought has been dwindling for decades as conflicts have become more complex and weapons more destructive. To some observers, the clearest sign yet of the framework’s fall from favor came in May, when Pope Leo wrote in his encyclical Magnifica Humanitas that it is “outdated.” A month later, 178 cardinals met at the Vatican to discuss whether the Church should move away from the language of just war. Still, many Catholics support the theory and dispute the suggestion that it’s passé. They believe that it was, and remains, the best way the Church has to make sense of war. At the center of the debate is a deeper question: How can the Church help limit violence in an all-too-violent world, in which nuclear bombs, terrorist attacks, and AI-guided drones are ever-present threats?

Just-war theory isn’t just the stuff of papal encyclicals. Military academies teach courses and host conferences about it. Human-rights laws are in part derived from it. Prominent pundits and politicians have opposed and defended some of the largest conflicts of the past few decades on just-war grounds.

Since the mid-20th century, though, the Vatican has seemed more focused on promoting peace than on explaining the ins and outs of the theory. The Church has tended to emphasize nonviolence “as the first resort and oftentimes an effective alternative to the use of military force,” Gerard Powers, who directs the Catholic Peacebuilding Studies program at the University of Notre Dame, told me. Pope John XXIII wrote about the need for nuclear disarmament; Pope Paul VI made an impassioned anti-war plea at the United Nations; Saint John Paul II described war as “always a defeat for humanity.” Recent Catholic scholarship, moreover, has highlighted the Church’s role as a mediator in conflicts—between the Colombian government and the Revolutionary Armed Forces of Colombia, for example—and criticized just-war theory for being too focused on the ethics of war rather than on nonviolent ways of preventing it.

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Popes have also voiced doubts about how applicable just-war theory can be today. In 2003, the future Pope Benedict XVI said that “we should be asking ourselves if it is still licit to admit the very existence of a ‘just war.’” In 2020, Pope Francis wrote that “it is very difficult nowadays” to “speak of the possibility of a ‘just war.’” As critics of the theory have pointed out, modern weapons and tactics have far more destructive power than they had in the late Roman and medieval period, when just-war theory was formulated, which makes just-war principles especially difficult to apply. When a military uses aerial bombing, civilians are almost certain to be among the casualties. Autonomous weapons raise new questions about moral accountability, which is the core of any ethical theory.

Some critics also assert that just-war theory has been “ineffective or inadequate at preventing and restraining war,” as Eli McCarthy, a lecturer in theology at Georgetown University, told me. “Even if we see a war that looks like it might meet the just-war criteria,” he said, those same wars tend to “get us stuck in cycles of violence.” The United States entered World War II, for example, to respond to Japan’s attack on Pearl Harbor, to protect Europe against fascism and Nazism. That conflict also led to the Cold War and several proxy wars. America invaded Afghanistan after the 9/11 terrorist attacks killed thousands of civilians, but that war did not permanently rid the country of the Taliban, and escalated the War on Terror.

The Vatican’s zeal for peace and seeming ambivalence about just-war theory has drawn criticism, especially among a conservative contingent of American Catholics. In the early 2000s, the philosopher Michael Novak and the writer George Weigel contended that the Church’s reflexive opposition to war downplayed governments’ moral obligation to uphold order and keep their citizens safe from autocrats and terrorists. Weigel wrote that the post–World War II Church had adopted a “functional pacifism” that ignored centuries of just-war teaching. Novak suggested that the Church underestimated the asymmetries presented by terrorism: Ideologically motivated, non-state actors intent on destruction at all costs are unlikely to be moved by diplomacy and may well be stopped only by force. More recently, J. D. Vance admonished Pope Leo in April “to be careful when he talks about matters of theology,” after the pontiff’s criticism of the Iran conflict. “There is more than a 1,000-year tradition of just-war theory,” Vance said. To skeptics of just-war theory, these criticisms exemplify its biggest flaw: how susceptible it is to being interpreted too broadly, or co-opted for political goals. Novak and Weigel defended the invasion of Iraq on just-war grounds, as did Catholic politicians including Joe Biden and the late U.S. Representative Henry Hyde.

[Read: Pope Leo’s unsettling vision of the AI future]

Just-war theory’s defenders have answers to this objection and others. John Schwenkler, a philosopher at the University of Texas at Austin, told me that the fact that the theory is “only as good as those whose hands it is in” doesn’t invalidate it. Just-war theory, he said, was meant to be “a framework within which to reason and debate,” not a “decision manual” that provides ready-made answers. If anything, the sloppy use of just-war theory makes clarifying its criteria “more important than ever.”

Theorists have also applied just-war criteria to new technologies. After World War II, when popular opinion held that the use of atomic bombs in Hiroshima and Nagasaki had been a “necessary evil,” the Oxford University philosopher Elizabeth Anscombe argued against their use on just-war grounds. She and others maintained that the scale of destruction, though ghastly, was secondary: What mattered was that the United States had intentionally targeted civilians—and that was unjust. To the theory’s supporters, examples such as this show that it is neither overly permissive nor outdated; instead, it sets a high bar for the legitimate use of force and can be used to think about the ethics of novel technologies.

In Magnifica Humanitas, Leo wrote that just-war theory has “all too often been used to justify any kind of war,” even as he also affirmed “the right to self-defense in the strictest sense.” (Notre Dame’s Powers told me that “the Church has not become pacifist,” pointing out that Leo has supported Ukraine’s defensive war against Russia.) Catholic leaders and academics have interpreted this part of the encyclical in a variety of ways. In a video address delivered to attendees of a conference last month in Rome, Cardinal Robert McElroy, the archbishop of Washington, D.C., said that he understood the pope’s statement as a “remarkable transformation” toward “eclipsing the role of the just-war tradition.” The Catholic philosopher Edward Feser, however, told me that “there’s no rupture with traditional just-war theory,” since Leo “explicitly acknowledges that military action for the purpose of strict self-defense can be legitimate.” What’s not legitimate, Feser has written, are wars such as the one in Iran: those that, as he told me, are carried out under “expansive and vague” aims that seem to “shift from moment to moment.”

The Vatican now faces two challenges. It will need to clarify what it means, exactly, when it says that just-war theory is outdated. And if the Church does intend to move away from the just-war framework, it will need to offer a successor theory that better addresses the many moral challenges that modern-day wars pose.

In the early Middle Ages, when soldiers returned from battle, the Catholic Church would at times impose spiritual penalties called “penances” on them for injuring or killing someone. The particulars varied—being denied Holy Communion for a time, or being told to eat only bread and water on certain days. “I think it’s actually quite a profound thing,” Phil Klay, a Catholic writer and Iraq War veteran, told me about the practice. “You’d have to seek forgiveness even if you were in a just war.”

[Read: Pope Leo’s pro-life challenge to conservative Catholics]

This tension is at the root of the Church’s debates about just-war theory. Many supporters and critics agree that the theory is prone to abuse. They also agree that peace is precious. But their disagreement underlies how all wars, no matter how righteous, are tragic because they require killing people who, as Klay put it, are “made in the image of God.”

For now, the Catholic Church seems to be distancing itself from just-war theory even more overtly than in the past. At the September conference in Rome, Cardinal Charles Maung Bo, the archbishop of Yangon in Myanmar, told attendees that “we need a new paradigm” that recognizes nonviolence as “a more effective form of defence.” Cardinal McElroy said that Leo’s Magnifica Humanitas deemed that the theory “can no longer constitute an authentic pathway of moral guidance in the life of the Church.”

But earlier this year he also said that “there are times when military force is morally legitimate.” Most Catholics invested in the Church’s teaching on war understand that despots, fanatics, and the human urge to dominate can make war unavoidable. For all of its faults, just-war theory recognizes this. Any new Church teaching would need to contend with this reality too.

This article originally stated that one of the reasons the United States entered World War II was to end the Holocaust; in fact, the government was not fully aware of the Holocaust until after it entered the war.