ROME – In his most significant document to date, Pope Leo XIV addressed what he called a “culture of power” in which violence is favored over peace and limitless technological advancement is embraced at the expense of the human being, especially the poor.

In his new encyclical Magnifica Humanitas, released May 25, the pope cautioned that “Humanity is slipping into a violent culture of power, where peace no longer appears as a responsibility to be taken on, but as a fragile interval between conflicts.”

“Today, more than ever, without prejudice to the right to self-defense in the strictest sense, it is important to reaffirm that the ‘just war’ theory, which has all too often been used to justify any kind of war, is now outdated,” he said.

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The line will likely ruffle feathers among many political leaders in nations involved in war, especially in the United States, where officials, including Vice President JD Vance, a Catholic, have repeatedly invoked the church’s just war theory to defend the U.S.’s war in Iran.

An American, Leo XIV has repeatedly condemned the Iran war and other U.S. military operations.

In his encyclical, the pope argued that war is neither the only nor the immediate solution to disputes, and that “humanity possesses far more effective and capable tools for promoting human life and resolving conflicts, such as dialogue, diplomacy and forgiveness.”

“The use of force, violence and weapons reflects a relational poverty that always has disastrous consequences for civilian populations,” he said.

Magnifica Humanitas or “Magnificent Humanity,” was signed by Pope Leo May 15, the anniversary of the publication of his predecessor Pope Leo XIII’s landmark encyclical Rerum Novarum, outlining the church’s modern social doctrine.

The document, an anthropological reflection on the state of humanity and its challenges amid the boom in AI technology, frames the discussion about AI as a choice for humanity about what direction it will take.

Humanity, Leo says, can either “construct a new Tower of Babel,” trying to take the place of God, or it can “build the city in which God and humanity dwell together,” as in the biblical figure of Nehemiah, who, with the help of the Christian community, rebuilt the city of Jerusalem, which had been destroyed.

“It is an undertaking with God at the center, which rebuilds relationships before rebuilding with stones,” he said.

In this context, the main choice that humanity faces in the AI era, he said, “is not between a ‘yes’ or ‘no’ to technology, but rather between constructing Babel or rebuilding Jerusalem; between a power that claims to dominate the heavens and a people who work together in the presence of God to rebuild the walls of fraternal coexistence.”

Leo argues that modern technology must be grounded in the church’s social doctrine, prioritizing what is good for humanity over the economy or private interests.

He calls for greater regulation of AI technology by states and condemns the concentration of this technology and its profits “in the hands of a few,” saying that standards of transparency and a system of checks and balances ought to be imposed on the handful of private companies that develop AI.

Leo also weighed AI’s environmental impact, its effect on families and the world of labor, and made a firm appeal for women’s equal rights and pay, as well as for the use of AI in war.

AI and war

In the encyclical’s final chapter, Pope Leo offers an extended reflection on the “culture of power” and dominance of modern society, and calls for the construction of “the civilization of love” as an alternative.

He noted that the digital revolution is changing the nature of conflicts and the way wars are waged, especially with the increased occurrence of cyberattacks, information manipulation, influence campaigns and the automation of systems.

“What is created for defense can be rapidly repurposed for offense, and the fine line between protection and aggression becomes blurred,” he said, saying AI can enhance the protection of civilians and lower the threshold of force, or it can reduce civilians to mere statistics and “collateral damage.”

Pope Leo lamented that “a culture of power is taking hold” in modern times in which “the availability of resources and the ability to dominate tend to dictate the agenda and criteria for decision-making.”

“This culture of power infiltrates society, changes relationships and behaviors, and grows by normalizing war, pursuing ever-greater military power, taking advantage of the crisis of multilateralism and fueling a false realism that insists that there is no alternative,” he said.

To this end, the pope lamented the revival of war as an instrument of international politics, saying a loss of historic memory is allowing the past to repeat itself.

“Regional conflicts that drag on over time, escalating tensions and reciprocal threats are becoming almost commonplace, and forms of conflict driven by the desire for territorial expansion that were thought to be overcome are re-emerging,” he said.

Along with this trend, Leo lamented that public opinion is gradually “being shaped and conditioned by polarizing media narratives, which are often amplified by algorithms that prioritize conflict and confrontation.”

In this sense, “war is not only fought, but also culturally conditioned through simplistic narratives, a friend-or-foe mentality, disinformation and fear,” he said.

With fewer Holocaust survivors and witnesses of the great World Wars alive to recount the horrors of war, he said, noting that the growth in military might now characterizes the current political landscape and the military-industrial complex now forms a significant sector of the economy for many countries.

The “close link between economic interests, the military apparatus and political decisions” has made war seem like a natural extension of politics, he said, calling the arms trade an “autonomous driving force behind military decisions.”

“Nor can we ignore the enormous economic interests behind war. The armaments industry, and countries that supply weapons, profit from a market that thrives precisely on conflicts,” he said.

While the threat of weapons that could destroy humanity was previously a reason to engage in negotiation and restraint, nuclear arsenals have now grown, and their use seems “less improbable,” the pope added.

To this end, Pope Leo pointed to the 2021 Treaty on the Prohibition of Nuclear Weapons, signed by over 70 countries, but lamented that it risks being “largely symbolic” since the major nuclear powers have not adhered to it.

“This has led to the widespread yet erroneous belief that nuclear deterrence is an indispensable prerequisite for security,” and it has also led to “a new arms race” that is hard to control and which is accompanied “by the gradual dismantling of nuclear reduction agreements,” he said.

Jihadist groups, private militias, and criminal networks compound the problem, signaling and end to a state monopoly on force of arms, he added.

With AI playing an increased role in weaponry and weapons systems, human oversight and control of war is being reduced, signaling a violation of “the principle that armed force should be used only as a last resort in cases of legitimate self-defense,” he said.

“No algorithm can make war morally acceptable,” he continued, saying AI systems do not remove “the intrinsic inhumanity of conflict.”

“Indeed it can only bring about conflict more quickly and render it more impersonal, lowering the threshold for resorting to violence, transforming defense into threat prediction and thus reducing victims to data,” Leo said, saying this “will accustom us to the idea that violence is inevitable and needs only to be optimized.”

AI systems still require a sound set of values in their programming, but that alone will not solve the problem, the pope said, saying “It is not enough to invoke a generic type of ethics. Concrete criteria for discernment must be established.”

He emphasized the importance of maintaining a sense of personal responsibility and taking time to conduct a serious evaluation of options before acting, without expediting the process, to ensure greater human control and the protection of civilians and essential infrastructure.

Pope Leo lamented the current crisis in multilateralism, saying international organizations such as the United Nations “are essential instruments for promoting a civilization of love,” as they can promote dialogue and the peaceful resolution of conflicts.

He voiced the Holy See’s support for the UN and its ability to protect the vulnerable, minorities, and to promote disarmament, “while also recognizing that the current weaknesses of the UN and the international political system reveal the need for profound reforms.”

Ecumenical and interreligious dialogue also play a key role in promoting the peaceful resolution of conflicts, the pope said, saying, “at the heart of the great spiritual paths lies a message of peace.”

“Whereas those who use the name of God to legitimize terrorism, violence or war betray his true nature, for to fight in the name of religion means attacking religion itself,” he said.