Carlo’s journey to sainthood advanced after Pope Francis recognized a miracle attributed to him in 2020, which led to Carlo’s status as “blessed.” This recognition came after Matheus Vianna, a 7-year-old Brazilian boy, was healed from a rare pancreatic ailment following contact with one of Carlo’s T-shirts.

That path was further paved last year when Carlo was attributed with a second miracle, in which he was credited with the complete healing of Costa Rican student Valeria Valverde from major head trauma sustained in a bicycle accident, after her mother prayed at his tomb.

But from an early age, Salzano said, he taught himself how to program computers and was asking her to buy books trained engineers might use. “He had a special skill, probably something unbelievable. I couldn’t understand how it would be so. But he used what he had in the heart, the love of God, to maximize for spreading the faith,” she added.

Using the family’s small, old computer, Carlo taught himself how to program and built a website cataloging more than 100 Eucharistic miracles around the world that had been recognized by the church over many centuries.

But while programming was his passion, Salzano said, she thought he would likely have become a priest as he had asked her about pursuing a career in the church. After receiving his First Communion at the age of 7, he attended daily Mass regularly and taught catechism in a local parish.

“He wanted to help people to discover their faith, to discover God, the love of God. And all his life was spent for this. Even if he lived a normal life, like young boys of his age,” she added.

At just 15 years old, in October 2006, he fell ill and within 10 days died of acute promyelocytic leukaemia.

While his suffering caused her a lot of pain, Salzano said, “if we leave suffering, offering to God, we can be in a certain way a little savior, like Jesus, we can help other people with our prayers.”

While she misses her son, she added that she had faith and she knew “that death is to say goodbye, not the end of everything. But death, as Carlo used to say, is the start of the true life.”

In 2018, Carlo was named “venerable” after the church recognized his virtuous life, and his body was taken to a shrine in the Santuario della Spogliazione in the small town of Assisi in central Italy.

He asked for that to be his final resting place because of his devotion to the medieval saint, St. Francis, whose hometown was Assisi. Wearing a track top, jeans and sneakers, he lies there entombed with a wax mold of his likeness placed over his body.

Today it is a popular devotional site, attracting thousands of worshippers every day, Monsignor Anthony Figueiredo said in an interview earlier this year.

“This is a saint in front of our eyes, and he’s a different kind of saint, you can see with jeans and sneakers and a hoodie exactly as he dressed,” he said, adding that Carlo had been inspired by by Apple founder Steve Jobs, who had said that at the end of each day, he had wanted to know he had “done something wonderful for someone else.”

“That really sums up Carlo,” Figueiredo said, adding that the teenager really strove to do something differently. “One of Carlo’s sayings, ‘All of us are born originals, but so many of us end up as photocopies.’ We just want to be like the crowd and be like others. And Carlo said, ‘you need to be original.’”

Explaining Carlo’s popularity, he recounted an interaction with a Mexican student who told him, “I cannot wear the sack cloth of Francis of Assisi. I cannot do the penances of Claire of Assisi, but I do have a pair of jeans, and I do wear trainers.”

Sunday’s ceremony in front of the Vatican’s St. Peter Basilica, in conjunction with the celebration of the Holy Year’s jubilee for teens, was originally set for April but was postponed after the death of Francis, who called the internet a “gift from God” and encouraged the Vatican to use technology.

It will be the first time Leo, elected in May to replace Francis, has presided over such an event.

It is impossible to quantify exactly how many saints there are. During the church’s first 1,000 years, they were proclaimed by popular demand, but some estimates have the number exceeding 10,000.

Other saints who died at a young age include Therese of Lisieux, who was known for promoting a “Little Way” of charity and died at 24 in 1897, and Aloysius Gonzaga, who died at 23 in 1591 after caring for victims of an epidemic in Rome.

As for Carlo, his mother said that she thought her son was “a sign of hope” and that it was “important to remind young people that they are unique.

“Like Carlo did, he could become holy in this world,” Salzano said. “You too can do the same. You too can overcome this and can do important things as well.”