Speaking during meetings with French President Emmanuel Macron and other officials at the Élysée Palace, Leo raised concerns about the ethical implications of scientific progress and posed broader questions about what it means to be human in an era increasingly shaped by artificial intelligence, warfare and threats to human life.

The pope later addressed diplomats and United Nations employees at UNESCO headquarters in Paris, where he emphasized the importance of ensuring technological development remains centered on human dignity and fundamental rights.

Against the backdrop of ongoing conflicts in Europe and the Middle East, Leo also reaffirmed the Vatican’s longstanding opposition to nuclear weapons and criticized the doctrine of nuclear deterrence, arguing that it contributes to a renewed arms race.

“Peace is not a balance of power; rather, it is built day by day through dialogue and justice,” Leo said.

The pontiff’s visit comes as the Catholic Church navigates France’s deeply rooted tradition of secularism, which limits the role of religion in public institutions and political life.

Despite that backdrop, thousands of people lined the pope’s motorcade route, waving French and Vatican flags as they waited in unusually hot weather to see him.

The trip marks the first official state visit by a pope to France in 18 years.

Later Friday, Leo attended an evening prayer service at Notre Dame Cathedral, where worshippers gathered for a ceremony featuring choirs and the cathedral’s organ.

Senegalese Sister Antonia Faye, attending an event with a pope for the first time, described the experience as strengthening her faith.

“To see him, praying with us, it comforts us in our faith and on our path,” she said.

Leo’s four-day visit is expected to continue focusing on peace, technology, human dignity and the role of faith in an increasingly secular society.