The Prince of Peace and the Sword of History: Pope Leo XIV, Just War, and the Christian Tradition
by Tim Rosenberger
I.
The confrontation between Pope Leo XIV and President Donald Trump over the American-Israeli war with Iran has generated considerable heat and rather less light. Trump called the first American pope weak and terrible for foreign policy. Leo responded that he had no fear of the Trump administration and would continue to preach the Gospel. The cycle looks like a political spat. In truth, it surfaces an ancient disagreement in Christian thought about faith and the use of force, a question the tradition has never fully resolved and that Leo has now restated at volume without reckoning with its implications.
Both figures deserve more charity than the exchange has produced. Trump’s instinct that a civilization under existential threat from a nuclear-armed adversary has the right and duty to defend itself is not theologically illiterate. It is the settled position of the Catholic Church whose leader is criticizing him, and in this exchange the president finds himself, improbably, its defender. Leo’s instinct that invoking divine blessing on the destruction of an entire people is politically reckless and spiritually dangerous is also not wrong. The positions become incompatible only when Leo reaches for language more absolute than the tradition warrants and Trump for divine endorsement more confident than any statesman should claim.
II.
Leo’s recent statements have followed an unfortunate arc. On Palm Sunday he said that Jesus “is the king of peace, who rejects war, whom no one can use to justify war,” adding that God “does not listen to the prayers of those who wage war but rejects them.” On social media he wrote that “God does not bless any conflict” and that no disciple of Christ “is ever on the side of those who once wielded the sword and today drop bombs.” He supported these claims with a citation from Isaiah 1:15, in which God tells Israel he will not listen to their prayers because their hands are full of blood.
These statements deserve a more careful reading than the political exchange has given them. The claim that God does not listen to the prayers of those who wage war is one I cannot find any pacifist tradition actually defending. Taken literally, it nullifies the prayers of every Christian soldier who ever prayed for God’s protection, and those of every priest who ever ministered to a dying soldier making his peace with God. To advance it as papal teaching is to claim that the prayers of every Catholic sailor at Lepanto, every Union chaplain at Gettysburg, every G.I. and Tommy kneeling before Normandy, and Billy Graham across half a century with American presidents, went unheard in heaven. It contradicts the pastoral practice of the Church in every war through which it has ministered.
The Isaiah citation deserves closer attention than it has received. The prophetic critique in Isaiah 1 is directed not at war but at a people who combined ritual observance with social injustice, bringing sacrifices to the temple while oppressing the poor and the widow. “Your hands are full of blood” is a charge of moral hypocrisy against a religious establishment, not a categorical indictment of military force. The same tradition that produced Isaiah also produced Joshua’s campaigns and the books of Maccabees, which sit inside the Catholic canon precisely because the Church has never read scripture against itself in this way. One suspects the verse was originally set aside for a different quarrel, perhaps a homily condemning immigration enforcement, and reached for without anyone checking.
“No one can use Christ to justify war” is not an exegetical argument. It is a doctrinal claim, and it stands in direct contradiction to the settled teaching of the Catholic Church over which Leo presides.
III.
The just war tradition is not a compromise between Christian ethics and political necessity. It is the product of taking the moral stakes of violence seriously enough to specify, with legal precision, the conditions under which violence is nonetheless permitted. Augustine argued that love of neighbor could require the use of force. Aquinas systematized the framework around legitimate authority, just cause, and right intention. The Salamanca School (Vitoria, Suárez) translated it into the jus gentium that founded modern international law, and Grotius carried the same structure into the Protestant and secular world.
Vatican II’s Gaudium et Spes preserved it while emphasizing proportionality. The Catechism codifies it at paragraphs 2307 through 2317, and those paragraphs reward a closer reading than Leo’s homilies have invited.
The Catechism urges prayer for peace, and then states that “governments cannot be denied the right of lawful self-defense, once all peace efforts have failed.” The right is not grudgingly tolerated; it “cannot be denied.” Paragraph 2309 sets out the four jus ad bellum criteria (grave and lasting damage, last resort, serious prospects of success, proportionality) and expressly reserves their evaluation to “the prudential judgment of those who have responsibility for the common good,” that is, to statesmen, not to bishops and not to the pope. That reservation is a remarkable concession in a document not otherwise famous for reticence about papal authority, and one Leo appears to have forgotten or to be purposely flouting. Paragraph 2310 teaches that soldiers who carry out their duty honorably are “servants of the security and freedom of nations” who “truly contribute to the common good.” This is not the language of an institution that believes God refuses to hear warriors’ prayers. Paragraphs 2312 through 2314 set out the jus in bello principles of discrimination and proportionality, largely tracking the Geneva Conventions and customary international humanitarian law. Paragraph 2316 authorizes regulation of the arms trade but assumes, without embarrassment, a legitimate arms industry. Paragraph 2317 locates the roots of war in “injustice, excessive economic or social inequalities, envy, distrust, and pride,” a diagnosis Leo has in fact echoed. Nearly every one of the preceding paragraphs, however, contradicts something he has said in the past three weeks.
Jean Bethke Elshtain pressed the Augustinian point with force in Just War Against Terror: the love commandment does not merely permit but can require the protection of the innocent through force. Elshtain, writing as a Lutheran political theorist deeply engaged with the Catholic tradition and cited widely in international law scholarship, was no enthusiast of American power. She saw clearly that a pacifism unwilling to confront the reality of aggression does not end injustice but reassigns its victims. That argument is not easily answered by papal fiat.
Aquinas is the deeper problem. Leo quoted him with approval at the Vatican Tribunal just weeks before the Iran war escalated. The natural law framework he invoked there leads directly to conclusions about just war Leo is not drawing. A prince who fails to use the sword to protect his people from grave injustice fails in his duty. Having dragged the Angelic Doctor out of the attic for natural law, Leo may come to regret that Aquinas has a great deal more to say.
IV.
There is a pacifist strand in Christian history, and the Christians who have held it with full consistency deserve genuine respect. The Anabaptist tradition, represented today by the Mennonites and the Amish, holds categorically that Christian discipleship excludes participation in war or in any form of violence. Within Catholicism the purest twentieth-century expression was the Catholic Worker movement, founded by Dorothy Day, whose political commitments sat well to the left of the Church’s magisterium.
The witness of the consistent pacifists is not easily dismissed. Their refusal of the sword stands as a rebuke to Christians who reach for coercive means too quickly. But a rebuke is not a doctrine, and a personal witness is not a magisterium. What distinguishes the Mennonites from Leo’s position is that they have accepted the cost of their conviction. They do not run states. They refuse to serve in the military and accept the legal consequences of that refusal. They do not accept the protection of armed guards.
The Catholic Church is not a Mennonite community. Catholic men serve in the military in every country where Catholics live, and the Church supplies chaplains to attend to their spiritual needs. Leo both presides over a sovereign state and is protected by the Swiss Guard, an elite commando squad with modern weaponry hidden beneath their flamboyant costumes, charged with using lethal force to defend the pope. The pope who proclaims that no disciple of Christ is ever on the side of those “who once wielded the sword and today drop bombs” has armed men standing outside his bedroom door.
A liberal Catholic reader will object that the historical argument proves too much, since post-conciliar popes have contradicted immemorial teaching on a number of matters, from religious liberty and usury to, in Francis’s case, capital punishment. Benedict XVI distinguished a hermeneutic of continuity from a hermeneutic of rupture, favoring continuity; Francis preferred rupture. But even rupture requires the formal work of doctrinal development. Francis changed the Catechism text on capital punishment, published his reasoning, and left a paper trail. Leo so far has issued only homilies and social media posts. His soon-to-be-published first encyclical, Magnifica Humanitas, is dedicated not to questions of war and peace but to the ethical challenges posed by artificial intelligence. If Leo intends to repudiate the Catechism’s just war doctrine, the honest and legally coherent path is to say so and defend the change through the ordinary magisterium. Homilies, however heartfelt, are not development of doctrine.
V.
The Protestant and Orthodox traditions offer useful triangulation. Luther’s two-kingdoms theology sidesteps the question of whether God condones violence by dividing God’s reign into two realms: the spiritual, governed through the Gospel and grace, and the temporal, governed through law and the sword. A Christian soldier acts as an agent of the temporal order, not as a disciple of the Sermon on the Mount. The kingdoms must not be collapsed. A commander who claims God’s specific blessing on his campaign makes the same category error as the categorical pacifist, from the opposite direction, by baptizing coercive power with transcendent authority it does not possess.
Eastern Orthodoxy occupies a distinct and underappreciated position. It has no formal just war doctrine, nor is it pacifist. What it has is closer to “justifiable but never truly just” war: violence may be permitted as a tragic necessity but is never celebrated. Canon 13 of St. Basil the Great counsels that soldiers who kill in war, even legitimate war, be excluded from communion for three years as a penitential discipline. The canon was never universally enforced, but the claim is clear: killing, even when permitted, incurs a spiritual cost requiring cleansing. The Russian Orthodox Church under Patriarch Kirill has in recent years done precisely what the tradition warns against, blessing Russian military action in Ukraine and framing it as civilizational warfare. The damage to Russian Orthodoxy illustrates what happens when “justifiable but not just” collapses into crusade theology. It should give pause to anyone who reaches too quickly for divine endorsement, including a pope who reaches in the opposite direction too quickly for divine prohibition.
VI.
Carl Schmitt observed that politics cannot be reduced to moral categories because it rests on a friend-enemy distinction that universal moral claims do not dissolve but merely relocate. A state that claims to fight not an enemy but a criminal, not a war but a crusade, has not transcended the political; it has moralized it. Leo’s version runs formally in the opposite direction and practically in the same one.
When Leo says no disciple of Christ can be on the side of those who “once wielded the sword and today drop bombs,” the language is universal, but the application has been conspicuously one-sided. The Islamic Republic of Iran has waged proxy war against the West since 1979. It arms and directs Hezbollah, Hamas, and the Houthis. Its mining of the Strait of Hormuz inflicts far greater harm on the developing world’s poor, those the Church rightly cares about, than on Western militaries. It has pursued a nuclear weapons capability defying the Non-Proliferation Treaty. Leo has not addressed any of this with comparable intensity. He has reserved his categorical moral language for the American and Israeli response.
This is the familiar pattern of the Cold War peace movements. Campaigns like the Campaign for Nuclear Disarmament framed themselves as bilateral calls for disarmament, but the practical effect ran one way: mass rallies in London and Bonn, silence in Moscow, and pressure for Western unilateralism that would have left the Warsaw Pact’s nuclear superiority undisturbed. Formal universalism paired with selective application is partisanship laundered through transcendent language. Schmitt saw this pattern clearly a century ago, and it is what Leo, intentionally or not, has reproduced.
VII.
The second observation is about asymmetry. Christianity is the only major world tradition in which categorical nonviolence has emerged as a serious internal option. Islam has its own well-developed jurisprudence of war and peace, with meaningful constraints on the conduct of warfare, though it draws different rules for conflicts among Muslims and with non-Muslims, and has produced no historic peace church along Mennonite or Quaker lines. The fourteen centuries of encounter between Christianity and Islam have been, in significant part, a military encounter. Catholic Europe fought off successive Islamic incursions at Tours under Charles Martel, at Lepanto, and at the gates of Vienna, and survived as Catholic because it fought. Eastern Europe, pressed in turn by Islamic and later Soviet power, did not fare as well. A Church committed to categorical pacifism in such a world would face a situation history has rarely resolved in the pacifist’s favor. Leo’s language, taken seriously, would require Catholics to accept that asymmetry as a condition of discipleship, and nothing he has said suggests he has thought through what that would mean for the Church he leads or for Western civilization.
The pacifists may still be right. The Mennonites who survived Soviet collectivization and Nazi occupation without arms are a witness with which the tradition must reckon. Their wager on divine protection is not irrational, but such protection is miraculous, and ordering a Church around the expectation of miracles is a presumption the natural law tradition has consistently warned against. If the pacifists are right, we will need miracles, and no magisterium can bind Catholics to that wager by homily.
The most honest thing Leo could say would not be that God never blesses conflict. It would be closer to this: the Church has lived in the tension between Gospel and sword since Constantine; the tradition has developed a precise legal grammar, preserved in the Catechism and in centuries of canon and international law, for acknowledging that tension; and any revision of that grammar must be done in the forms the tradition recognizes, through encyclical and council, not through homily and social media. Until then, paragraphs 2307 through 2317 remain the teaching of the Church, and the pope who departs from them in practice while leaving the text in place departs from his own magisterium.
Topics: Reflections & Dialogues
Tim Rosenberger is a pastor and attorney and cofounder of Excelsior Action.