“Just like Laudato Si’ was not a climate change encyclical, this will not be an AI encyclical, even if its central case study, in a way, is AI,” said a Vatican source familiar with the document’s drafting ahead of its release, referencing Pope Francis’ 2015 encyclical that reflected on modern humanity’s relationship with the environment.

Almost half of the Magnifica Humanitas is dedicated to tracing the development and foundational principles of the church’s social teaching from Rerum Novarum, the industrial revolution-era encyclical penned by the pope’s namesake, Pope Leo XIII, through Pope Francis.

The pope has had AI on his radar from the onset of his papacy, telling the cardinals who elected him that in today’s age, the church is called to offer “the treasury of her social teaching in response to another industrial revolution and to developments in the field of artificial intelligence that pose new challenges for the defense of human dignity, justice and labour.”

More than one year later, Leo’s first encyclical draws heavily from the documents of the Second Vatican Council and previous papal encyclicals to justify the church’s public engagement in debate over technological development, even when it does not fit squarely into its spiritual domain.

“Technology is never neutral, because it takes on the characteristics of those who devise, finance, regulate, and use it,” Leo wrote. AI developers, therefore, “bear a particular ethical and spiritual responsibility, for every design choice reflects a vision of humanity.”

One of Leo’s most robust criticisms of AI takes aim at the concentration of power among a technocratic class of AI developers. To make his case, Leo invokes the principle of subsidiarity, which holds that social and political decisions should be made at the most local level possible.

The pope insisted on the development of AI systems, “the possibility of openly discussing the ethical frameworks involved and subjecting them to shared standards of social justice.”

“Communities and intermediary organizations must not be reduced to passive recipients of decisions made elsewhere; they must be able to contribute to discernment and oversight,” he wrote. “Moreover, ownership of data cannot be left solely in private hands but must be appropriately regulated.”

Amid technological changes that push humanity toward a “violent culture of power” through polarization and the erosion of ethics, Leo acknowledges the right to self-defense but challenges the church’s teaching on just war, a teaching that recently made headlines during debates over the United States-led war effort in Iran.

“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,” Leo wrote.

Although Pope Francis had previously rejected invoking just war theory to justify “preventive” acts of war, Leo’s statement goes further in asserting that technological developments have decidedly altered the moral conditions on which just war theory had been formed.

Though the pope did not provide his own parameters for an updated understanding of just war, he wrote that today, “humanity possesses far more effective and capable tools for promoting human life and resolving conflicts, such as dialogue, diplomacy, and forgiveness.”

After U.S. President Donald Trump’s virtual tirade directed at the pope over his condemnation of the war in Iran, Vice President JD Vance, a Catholic, questioned Leo’s understanding of just war theory. Various members of the global Catholic hierarchy, including Washington Cardinal Robert McElroy, have said the war in Iran does not meet the moral requirements to constitute a just war.

Leo identified a “paradigm shift” around public discourse of war in contemporary society, calling out the “troubling revival of war as an instrument of international politics” aided by polarizing media narratives, which are often amplified by algorithms that prioritize conflict and confrontation.

“War is not only fought, but also culturally conditioned through simplistic narratives, a friend-or-foe mentality, disinformation and fear,” he wrote. The pope also warned that the military-industrial complex has become “a defining feature of the current political landscape,” producing what he called an “armed nation” in which war appears as “a natural extension of politics.”

The pope condemned outright the surrendering of combat decisions to AI systems, writing that “it is not permissible to entrust lethal or otherwise irreversible decisions to artificial systems.”

Technology must retain a “chain of responsibility” in war settings “so that accountability and blame are not collapsed into ‘the machine,'” he wrote.

Leo asks pardon for the church’s delay in condemning slavery 

Leo also connected the AI economy to what he called “new forms of slavery,” arguing that the digital realm relies on the “silent work of millions” engaged in data labeling, model training and content moderation — often for minimal wages and under harsh conditions — and the labor of those working in the extraction of rare earth materials needed to produce the devices and microprocessors on which AI depends.

Embedded within the larger reflection on contemporary forms of slavery, Leo addressed the church’s own history of complicity with the slave trade, stating that Catholics cannot “deny or diminish the delay with which both society and the Church came to denounce the scourge of slavery.”

Despite the church’s consistent affirmation of universal human dignity, “it took eighteen centuries for its full incompatibility with slavery to be explicitly recognized,” Leo wrote. “For this, in the name of the Church, I sincerely ask for pardon.”

Numerous papal bulls issued in the Age of Discovery explicitly granted colonizers the right to enslave Indigenous peoples. It was not until 1839 that Pope Gregory XVI called the slave trade “inhuman” and “unworthy of the Christian name.”

Leo’s apology, on behalf of the church and inserted into a magisterial document, constitutes a more direct mea culpa explicitly from the institutional church.

Economic consequences of AI

Warning against the potential human costs of widespread unemployment brought about by the integration of AI into the work force — a 2025 MIT study estimated AI could replace 11.7% of the U.S. workforce — Leo wrote, “technological progress will inevitably produce structural inequalities” if efforts are not made to prevent further disparities, “including tax systems that lighten the burden on the weakest and ask for more from those with greater resources”

“The pursuit of greater profits cannot justify choices that systematically sacrifice jobs,” he wrote, “because the human person is an end, not a means, and the economic order must remain subordinate to human dignity and the common good.”

Leo then called for transparency in how “data and algorithms influence credit distribution, personnel selection or access to services and opportunities,” and said society must invest in the skills of individuals “to ensure that technology does not widen the gap between those who have and those who have not.”

Acknowledging the church’s historic support for labor unions, the pope said organized labor is called to represent and defend workers while also being “open to new types of employment and the corresponding needs of workers.”

The pope also lodged a broader critique of the economic benchmarks used to measure societal progress: “It is important to move beyond the current metrics of development — which for more than eighty years have been tied to the concept of Gross Domestic Product (GDP) — since these metrics almost systematically neglect aspects essential to the overall well-being of people and the environment.”

 AI-fueled misinformation weakens democracy

Touching on disinformation, which “finds a powerful amplifier in AI,” Leo said, “democratic life is weakened” when truth is not pursued by a society.

“Indifference to the truth leads, slowly but surely, to a descent into totalitarianism,” he wrote.

The pope wrote at length on the essential nature of truth in communication, ranging from the prophetic to the purely practical and highlighting the key role of education in orienting individuals toward truth.

Leo urged society to “exercise restraint in the use of AI and to protect our young people from the promise of the perfect machine, from that subtle temptation which renders human thought seemingly superfluous precisely when it is most needed.”

“Having a personal mobile device at too early an age and using it without adult supervision can exacerbate young people’s vulnerabilities, foster addiction and expose them to isolation, bullying and cyberbullying, as well as to pressures to share intimate images or sensitive information,” the pope wrote.

Leo also identified how, although young people acquire knowledge in schools, they also demonstrate an “inability to connect information with deeper knowledge or maintain a sense of purpose,” urging educational models that “incorporate silence, in-depth study, reading and judicious analysis.”

Addressing transhumanism and posthumanism

The pope also pushed back against currents of transhumanism and posthumanism, warning against visions of progress that treat human limitations as problems to be surpassed.

Transhumanism generally seeks to extend human capacities beyond their biological limits, while more radical forms of posthumanism challenge the idea that the human person should remain the central reference point for ethics.

“If the human being is treated as something to be perfected or surpassed, it becomes easier to accept that some lives are less useful, less desirable, or less worthy,” the pope wrote. “In the name of progress, ‘necessary sacrifices’ may begin to be justified, placing the burden on the most vulnerable in pursuit of a supposed optimization of the species.”

In the encyclical’s most sustained reflection on the spiritual implications of technological development, Leo exalted human experience, stating that “humanity flourishes not despite limitations, but often through them.”

He wrote that it is within their human limitations that people are led to compassion, generosity, “spiritual experience and the worship of God.”

Leo noted how certain works of art communicate, through an expression of limitations, the principle of human fraternity and push back against injustices which threaten it, explicitly citing Beethoven’s “Ninth Symphony,” “Guernica,” and “Schindler’s List.”

Christian self-transcendence, on the other hand, is sought “through an escape from reality or a contempt for their limitations, but through their fulfillment in love,” he wrote.

“For an algorithm, an error is a flaw to be corrected; for a person, however, an error can be a catalyst for profound change,” the pope wrote.

The long arc of Catholic social teaching applied to AI

Atypical for an encyclical, Leo spends almost half of his first major teaching text recounting the principles and development of the church’s social teaching through history to avoid his teaching “being perceived as an undue interference in ‘worldly’ matters or as an external code of ethics imposed from above.”

“In reality, it stems from a Church that walks alongside humanity, recognizing the autonomy of earthly realities and the distinction between ecclesial and political communities,” the pope wrote.

Leo applied the core principles of Catholic social teaching to the rapid pace of technological development, offering them as a moral framework for deciding how new technologies should be designed, governed, and applied.

Articulating the principle of the universal destination of goods, which Catholic teaching holds as superior to the right of private property, the pope said that among the goods intended for all “must also include new forms of property, such as patents, algorithms, digital platforms, technological infrastructure, and data.”

“In a context where the wealth of nations depends increasingly on knowledge and technology, when these goods remain concentrated in the hands of a few, without adequate forms of sharing and access, a new imbalance is created that contradicts the universal destination of goods,” he wrote.

Leo also warned that the concentration of power among major economic and technological actors threatens the principle of subsidiarity, particularly among “companies and platforms that define conditions for access, rules of visibility, forms of interaction, and even economic opportunities.”

“We cannot allow a handful of actors to dictate these processes on their own; instead, we must build forms of cooperation that respect the various levels of the global community and make them jointly responsible for the common good,” he wrote.

At the core of the church’s social teaching, Leo stated that for all Christians, “going beyond the narrow confines of one’s own interests and committing oneself, within the limits of one’s ability, to the common good is a non-negotiable value, as is the promotion of life.”

Despite the scale of challenges confronting humanity, the pope asserted that “no one is without responsibility” in shaping humanity’s response to the age of AI, and warned of a “polite form of resignation, often disguised as realism” which disengages people from the moral questions posed by new technologies.

Concretely, the pope asked people to be conscious about their use of language, to give space to the victims of injustice, engage in dialogue, revive diplomacy and multilateralism, and pray for peace in relationships and society.

To illustrate his call, Leo quoted Gandalf from J.R.R. Tolkien’s Lord of the Rings, in which the wizard describes the characters’ responsibility for “uprooting the evil in the fields that we know, so that those who live after may have clean earth to till.”

Calling all people to action, Leo wrote, “The civilization of love will not arise from a single or spectacular gesture, but from the sum total of small and steadfast acts of fidelity that serve as a bulwark against dehumanization.”