VATICAN CITY. Pope Leo XIV on Sunday declared Carlo Acutis, a 15-year-old computer whiz who used technology to spread Catholic faith, as the Church’s first millennial saint.

The canonization took place during an open-air Mass in St. Peter’s Square before an estimated 80,000 people, many of them millennials and families with young children. It was the first saint-making Mass of Leo’s pontificate and also included the canonization of Pier Giorgio Frassati, another popular Italian figure who died young.

Leo praised both Acutis and Frassati, saying they created “masterpieces” out of their lives by dedicating them to God. “The greatest risk in life is to waste it outside of God’s plan,” Leo said in his homily. The new saints, he added, “are an invitation to all of us, especially young people, not to squander our lives, but to direct them upwards and make them masterpieces.”

Born in London on May 3, 1991, Acutis was raised in Milan by a wealthy but not particularly observant Catholic family. From an early age he showed both a growing devotion to his faith and a strong interest in computer science, reading college-level programming books while still a child.

His most enduring legacy was a multilingual website cataloging Eucharistic miracles recognized by the Church, a project that earned him the nickname “God’s Influencer.” He was also known for spending hours in prayer before the Eucharist each day, while limiting himself to just an hour of video games per week.

In October 2006, Acutis fell ill with acute leukemia and died within days. He was entombed in Assisi, famously associated with St. Francis, where millions of young Catholics have since visited his glass-sided tomb. There, he is displayed in jeans, Nike sneakers, and a sweatshirt, appearing as if asleep. Questions have surrounded the preservation of his body, while relics, including parts of his heart, have toured the world.

His canonization was long championed by Pope Francis, who believed the Church needed a young, relatable saint to inspire Catholics in the digital age. The ceremony was postponed after Francis’ death in April, making it one of the first major acts of Pope Leo XIV’s pontificate.

“It’s like I can maybe not be as great as Carlo may be, but I can be looking after him and be like, ‘What would Carlo do?’” said Leo Kowalsky, an 8th grader at a Chicago school attached to the Blessed Carlo Acutis Parish. He added that he was especially excited that his namesake, Pope Leo, presided over the canonization.

Much of Acutis’ popularity stems from the Vatican’s effort to present him as a “saint next door” for the next generation. For many Catholics, he represents an ordinary young person who did extraordinary things with technology and faith.

The Vatican reported that 36 cardinals, 270 bishops, and hundreds of priests joined Pope Leo in celebrating the Mass, reflecting the widespread appeal of Acutis and Frassati. Hours before the ceremony, St. Peter’s Square was already filled with pilgrims, including many young Italians.

“I learned from different people what his professors, his teachers, said about his joy and the light he carried around him,” said Leopoldo Antimi, a 27-year-old Roman who arrived early to secure a spot. “So for me personally as an Italian, even on social networks that are used so much, it is important to have him as an influencer.”

Matthew Schmalz, professor of religious studies at Holy Cross College in Worcester, Massachusetts, said Acutis’ canonization reflects a new stage in Catholic spirituality. “He becomes an emblem or model of how Catholics should approach and use the digital world with discipline and with a focus on traditional Catholic spirituality that defies the passage of time,” Schmalz said. “He is a new saint of simplicity for the ever complex digital landscape of contemporary Catholicism.”

Frassati, also canonized Sunday, lived from 1901 to 1925 and died of polio at age 24. A member of a prominent Turin family, he became known for his devotion to the poor, his acts of charity, and his ability to inspire friends with his faith.