Carlo Acutis, a young Italian born in London who died in 2006 at the age of 15, was declared the Catholic Church's first millennial saint during an open-air Mass in a packed St. Peter's Square.

Pope Leo XIV thus declared the genius on Sunday of 15-year-old computer science as the Catholic Church’s first millennial saint, giving the next generation of Catholics a relatable role model who used technology to spread the faith and earned the nickname “God’s influencer.”

Leo canonized Carlo Acutis, who died in 2006, during an open-air Mass in St. Peter’s Square before an estimated 80,000 people, many of them millennials and couples with young children. During the first canonization Mass of his pontificate, Leo also canonized another popular Italian figure who died young: Pier Giorgio Frassati.

The first miracle attributed to Acutis occurred in 2013 in Campo Grande, Brazil, when a seven-year-old boy, stricken with a serious pancreatic disorder with no medical cure, was restored to health after coming into contact with a piece of a T-shirt that had belonged to the young man. The healing, considered miraculous by church authorities, was what led to her beatification.

The second miracle recognized by the Vatican occurred in May of this year and involved Valeria Valverde, a 21-year-old Costa Rican student. According to the Vatican, the mother made a pilgrimage to Acutis's tomb in Assisi to pray for the recovery of her daughter, who had suffered severe brain trauma after falling off a bicycle. After the visit, medical reports confirmed her recovery, a fact considered inexplicable by science and attributed to the Blessed's intercession.

"The greatest risk in life is to waste it outside of God's plan," said Leo XIV in his homily, noting that Acutis and Frassati had made their lives masterpieces by dedicating them to God. The new saints "are an invitation to all of us, especially young people, not to waste our lives, but to direct them upward," he stated.

Acutis, born on May 3, 1991, in London, earned the nickname “God’s Influencer” thanks to his main technological legacy: a multilingual website that documented so-called Eucharistic miracles recognized by the Church, a project he launched at a time when the development of such sites was the domain of professionals.

The canonization ceremony was the first presided over by Pope Leo XIV, the first American pontiff, with thousands of young people in St. Peter’s Square.

A large crowd gathered Sunday in Vatican City, waving signs and flags bearing Acutis’s photograph. Jubilant onlookers applauded after Pope Leo canonized the teenager.

The canonization of the young saints comes as the Catholic Church, led by an all-male hierarchy where leaders are typically over 60, is exploring new ways to connect with younger generations. A crisis involving the sexual abuse of minors and vulnerable adults by clergy has had a catastrophic impact on the Church’s credibility.

But while the long-term trend in the West suggests that young people are increasingly disengaged from the mainstream religion, recent surveys and anecdotal evidence point to a surge of interest in Catholicism among Generation Z in the United States and Europe.

Canonization typically follows a lengthy and detailed process, involving a painstaking investigation by the Vatican and outside specialists who determine the veracity of miracles attributed to the individual. Acutis’s beatification, a precursor to canonization, was carried out by Pope Francis in 2020.