Anthropic co-founder Chris Olah was in the audience as Leo presented his first letter on Catholic doctrine.
WASHINGTON — In the halls of the 400-year-old St. Peter’s Basilica of the Vatican, the focus on Monday was on a technology that’s in its infancy.
Pope Leo XIV presented a more than 42,000-word letter on artificial intelligence in his first encyclical as pontiff.
The letter was subtitled “on safeguarding the human person in the time of artificial intelligence.” Its title, the Latin phrase, “Magnifica humanitus” — Magnificent humanity.
Among its declarations, the letter featured a direct plea to AI developers to focus on “safeguarding humanity.”
“I wish to address a special appeal to those who develop artificial intelligence,” Leo writes. “In one sense, technological innovation can represent human participation in the divine act of creation. Developers, therefore, bear a particular ethical and spiritual responsibility, for every design choice reflects a vision of humanity.”
And this wasn’t a rhetorical appeal by the pope. Leo was joined in the Vatican by Anthropic co-founder Chris Olah, whose multi-hundred-billion-dollar San Francisco-based AI company is responsible for developing the large language model, Claude.
Theologians and clergy also greeted the pope, who presented them with “Magnifica humanitas” at around 11:30 a.m. local time on Monday.
What is an encyclical?
The papal encyclical is a letter sent out by the pope to all church leaders with the pontiff’s interpretation of Catholic doctrine. Having started his papacy in May 2025, Monday marked Leo XIV’s first encyclical as pope. Pope Francis, Leo’s predecessor, published four with his final in October 2024 titled “Dilexit nos,” meaning “He loved us.”
Monday wasn’t the first time Leo addressed AI during his papacy, though. In February, the pontiff asked priests in a closed-door meeting to “resist the temptation” to prepare homilies with AI, according to a report from Vatican News, adding that AI “will never be able to share faith.”
“Like all the muscles in the body, if we do not use them, if we do not move them, they die. The brain needs to be used, so our intelligence must also be exercised a little as to not lose this capacity,” Leo reportedly said.
And last Friday, Leo publicly addressed a Vatican conference on AI, decrying chatbots as exploiting a need for human relationships.
“We are truly experiencing an eclipse of the sense of what it means to be human,” Leo said last Friday.