Pope Leo XIV says control of artificial intelligence must not remain in the hands “of a few” while warning that technology is fueling world conflicts, setting out his proposals in the first major theological document of his pontificate.

These include protecting the distinctive “grandeur of humanity” amid rapidly changing technology and for the use of AI in warfare to be subject to “the most rigorous ethical constraints.”

While the encyclical focuses on AI, it is a text that goes beyond technological questions and touches on crises facing humanity. Pope Leo said that the “just war” theory – a four-pronged Christian doctrine stating what conditions justify war – is “now outdated,” saying that military force can only be used for “self-defense in the strictest sense.”

He adds that the “litmus test” for social justice is the treatment of migrants and refugees and offered an apology for the church’s legitimizing in slavery and delay in denouncing the scourge.

The pope, who has made peace-making a central feature of his pontificate, warns that the use of “force, violence and weapons” ultimately “has disastrous consequences for civilian populations.”

“The construction of a world in a state of perpetual conflict is an evil and must be named for what it is,” the pope writes, adding that, “Humanity possesses far more effective and capable tools for promoting human life and resolving conflicts, such as dialogue, diplomacy and forgiveness.”

His opposition to Just War follows remarks by US President JD Vance that the pope “be careful when he talks about matters of theology” after the Catholic spiritual leader fiercley criticized joint US-Israeli strikes on Iran and rebuked world leaders for invoking religious language to rationalize war.

Pope Leo reiterated that humanity must confront new challenges by “listening” to diverse perspectives and coming to reason, while presenting his manifesto to an audience at the Vatican on Monday.

“Artificial intelligence already touches many areas of our lives and affects decisions that shape human co-existence,” he said. “I feel entrusted to look upon another huge transformation with eyes of faith, with lucidity of reason, with openness to mystery and with cries of the poor and the earth resounding in my heart.”

Parallels between AI and ‘Tower of Babel’

In the text, the pope also calls for a series of principles to be applied to the development of AI, including a fairer distribution of resources, the dignity of the human person, social justice and care for the environment.

Drawing on a biblical story, the pope warns that with AI, humanity risks building a “Tower of Babel,” which was an attempt for people to “make a name” for themselves with a single power and one language. The pope says the story is a warning against a plan that “dominates and ultimately dehumanizes,” insisting instead that diverse opinions and groups should contribute to AI’s development.

Leo insists that the technology must protect peoples’ jobs and needs to be subject to “robust legal frameworks, independent oversight, informed users and a political system that does not abdicate its responsibility are required.”

An encyclical is traditionally a letter sent by the pope to the bishops and the wider Roman Catholic Church, but recently it has broadened with Pope Francis using the first encyclical of his papacy to address the whole world on protecting the environment.

Leo XIV’s document on AI, “Magnifica Humanitas” (“Magnificent Humanity”), is being seen as a similarly landmark text for his papacy, and as addressing an epoch-defining topic which he addressed to Catholics and “every person of goodwill.”

Pope Leo has identified AI as a top priority, and he is the first pontiff to personally present an encyclical letter to the world at the Vatican.

Past popes have normally handed that role of presenting an encyclical to cardinals or other senior figures. Instead, the pope oversaw the release of the 235-page booklet alongside Chris Olah, a co-founder of Anthropic, an AI company that has been in legal dispute with the Trump administration over the use of its technology in military and defense operations.

Olah echoed Pope Leo’s call for greater accountability of AI tycoons on Monday, saying that decisions “should not be left to people in the industry.” He listed three principles that require a collective resolution – including a “duty to the global poor,” “moral imagination and ambition” and the “need for discernment.”

“Every frontier AI lab, including Anthropic, operates inside a set of incentives and constraints that can sometimes conflict with doing the right thing,” Olah told an audience at the Vatican.

“If we want this technology to go well, it is enormously important that there be people outside those incentives … who are willing to be our earnest, thoughtful critics,” he added. “That is what I see in Magnifica Humanitas.”

The pope’s text outlines an approach to AI which neither rejects the opportunities offered by the technology, nor sees it as opening a utopia-style future. His encyclical seeks to offer the resources of Catholic social teaching – the engagement with political and civic life – to the discussion on AI. Leo’s prime concern is maintaining the centrality, and unique dignity, of the human person.

To that end, the first American pope issues a critique of “transhumanism,” the idea that technology can help a person overcome physical and biological limitations such as aging, and of “posthumanism,” which questions the distinctiveness of human beings and blurs the boundaries between humans and machines.

“We cannot consider AI to be morally neutral,” the pope writes. “Every technical tool embodies choices and priorities through what it measures, ignores and optimizes, and how it classifies people and situations.”

Pope Leo ultimately prescribes the disarmament of AI, not as a means of “rejecting technology” but rather “preventing it from dominating humanity.” That doctrine means “freeing technology from monopolistic control and opening it to discussion and debate, therefore making it human-friendly.”

Papal text is a ‘rallying cry’

The choice of Anthropic for the encyclical unveiling reflects the ongoing tensions between the Chicago-born pope and US President Donald Trump, who has launched a series of criticisms against the pontiff for his stance on the Iran war. The Trump administration has taken a hands-off approach to AI regulation, with the president deciding to postpone signing an executive order ensuring government reviews of new AI models, including Anthropic’s Mythos system.

Including Olah on the launch platform, however, shows the Vatican is seeking to directly influence those involved with developing the technology, and not to simply be talking from the sidelines. And a Vatican source said that Anthropic’s inclusion is “not an endorsement, prize, reward or canonization.”

Pope Leo has already addressed the topic of AI several times during his year-long papacy, warning against “overly affectionate” chatbots, sending a message to tech execs meeting on AI in the Vatican and urging priests not to use AI when writing their homilies.

A few days before the encyclical was released, the pope took the unusual decision to establish a cross-department Vatican commission on AI, which will examine the effects of the technology.

The rapid advance of AI may also have been a factor in Leo XIV’s choice of name. Speaking to the College of Cardinals soon after his election, the pope pointed out that that his namesake, Leo XIII, was remembered as the pope of Catholic social teaching – the church’s engagement with public life – during the time of the industrial revolution.

Leo XIII wrote the landmark encyclical, “Rerum Novarum,” in 1891, a wide-ranging text addressing workers’ rights, a fair wage and the right to private property. Leo XIV told the cardinals that he hoped to offer the Church’s social teaching in response “to another industrial revolution and to developments in the field of artificial intelligence.” He signed his AI encyclical on May 15, 2026, on the same day that Rerum Novarum was released 135 years previously.

“The time to talk about AI is now. It is urgent,” Anna Rowlands, a theologian from the University of Durham who spoke along with the pope at the encyclical’s launch, told CNN.

“The encyclical helps all of us – believers and non-believers – to ask the same fundamental question: what does it mean to be human in an age when human life faces an unprecedented challenge from the development of various technologies … this text is a rallying cry, a Gospel cry, to build together a civilisation of love and oppose a culture of mere power.”

The pope’s encyclical builds on the work already done by the Vatican on AI, including a dialogue with Silicon valley over the last decade and a push for greater regulation. Pope Francis also addressed world leaders on the topic when he became the first pope to speak to the G7 in June 2024. The Vatican’s doctrine and education offices last year issued a document highlighting AI-driven misinformation including deepfakes, while a theological commission released a detailed reflection looking at the threats posed by AI, transhumanism and posthumanism.

The Vatican has seen how AI can be used first hand. Pope Francis was the subject of several deepfake images, while Pope Leo revealed he refused to allow a “papal avatar” of him who would hold private audiences and answer questions.

But Father Antonio Spadaro, a Vatican official, says Leo’s encyclical is a new moment and marks the “most significant institutional response” to AI by a major global religious body, and perhaps the clearest signal yet that the Vatican intends to do more than issue intelligent warnings from the margins of debate.”

Now, the focus is on what happens next. Pope Francis timed his 2015 encyclical on the environment to influence the Paris COP21 climate summit, with the text gaining traction both inside and outside the Cchurch as inspiration for sustainability initiatives.

Leo will likely hope that his own text is not simply read and put on a shelf but is a document that can inspire meaningful action. (CNN)

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