PARIS — Pope Leo XIV warned Friday that a "paradise of machines" risked undermining humanity as he opened a trip to France by posing fundamental questions about what it means to be human in the age of artificial intelligence, a nuclear arms race and other threats to life itself.
Leo raised existential concerns about scientific progress, life and human rights during his opening speech to President Emmanuel Macron and authorities at the Élysée Palace and then to diplomats and United Nations employees at the headquarters of UNESCO, the U.N. culture and education organization.
With wars plaguing Europe and the Middle East, he reaffirmed the Vatican's opposition to nuclear weapons and said the nuclear deterrence doctrine was "mistaken" since it was just fueling a new arms race.
"Peace is not a balance of power; rather, it is built day by day through dialogue and justice," he said.
Leo has an intense four days in France, where the Catholic Church has lost ground on influencing ethical issues given the strict approach to secularism that is enshrined in the French Constitution.
Church bells tolled across the country when Leo's charter flight landed at Paris' Orly airport, and more than a million people are expected to turn out to see him. They lined the streets of the capital as Leo's motorcade passed by, underscoring the surprising level of interest in Leo's visit, the first official state visit by a pope in 18 years.
Macron said Leo's visit brings "a source of hope" to many French people.
"France stands on the side of peace, effective multilateralism, respect for international law and the United Nations Charter ... because every life has equal value, and all peoples must be defended," he said.
A capstone visit as Macron's term ends
For Macron, who is barred from seeking a third term in May elections, hosting the American pope is something of a capstone. Pope Francis had refused repeatedly to make a proper state visit to France during his 12-year pontificate and pointedly refused to join the inauguration of the rebuilt Notre Dame cathedral in 2024.
"For a president of the republic as Macron, who is at the end of his mandate, it can be important to be aside the pope and to capture a part of his popularity," said Charles Mercier, director of history and sociology of Catholicism studies at Paris EPHE university.
With seven months left in his term, Macron's approval ratings are near record lows, driven by anger over the rising cost of living and criticism of France's growing debt and deficit and deteriorating public services.
Smiling broadly as Leo spoke French, Macron thanked the pope for visiting, saying: "You are here with us for an extended visit, giving us your time, and that is moving."
The Rev. Aristide Ahidote, from Ivory Coast, was among those who planned to attend the pope's vespers service in Notre Dame later Friday. "God has given us a pope with vigor and strength," he said.
While acknowledging the French church has declined in popularity, Ahidote said "it still has small remnants and these small remnants have been edifying for me."
Leo appeals to loftier questions about life
Unlike Francis, who liked to travel to small Catholic communities far from Rome, Leo has been keen to emphasize and reawaken Europe's Christian roots. He is seeking to push the church's message about the value and dignity of human life in a country where the right to abortion was enshrined in the constitution in 2024, and where lawmakers recently gave final approval to a bill allowing adults with incurable illnesses to receive lethal medication.
The French Catholic hierarchy strongly opposed the measures, in keeping with Catholic teaching that human life must be protected and defended from conception until natural death.
In his speech to Macron and other government and diplomatic authorities, Leo reminded France of its "deep Christian roots" and called especially for the French to remember that the right to life is the "indispensable foundation of every other human right."
His concern about the dignity of human life and humanity as a whole extended to the threats posed by artificial intelligence.
"The paradox has become increasingly evident: while 'intelligence' is attributed to computational systems, we struggle to recognize the inalienable dignity of human persons, whose lives are judged according to the criterion of efficiency and, when deemed no longer productive, are rejected and discarded," he said.
From the very start of his pontificate, Leo has identified AI as one of the greatest challenges facing humanity. He dedicated his first encyclical to the topic, "Magnificent Humanity," calling for robust regulation and for AI developers to work for the common good rather than profit.
Leo also appealed to AI developers and political leaders responsible for regulating them to slow down, an appeal that several top AI companies seem to have taken to heart in recently.
"If we are to avoid losing our humanity amid a 'paradise of machines' invading and conditioning our daily lives, there is an urgent need for education in ethical discernment and the capacity to acknowledge the moral good," he said.
Speaking to reporters en route to Paris, Leo said he was pleased that his message was being heard and said he hoped the dialogue that the Vatican had initiated with tech companies would continue.
"And I think from their perspective, many of them, they're very much open to looking for ways of making sure that AI does not displace or ultimately destroy humanity, but rather than be a tool for human beings," he said. "Good things are beginning at least."
Copyright 2026 NPR