The Catholic Church will canonize two saints this weekend. Just how does someone become a saint?

A primer on miracles, martyrs, virtues

Lengthy historic investigations. Decrees of “heroic virtues.” Miraculous cures.

The Vatican’s complicated saint-making process has long fascinated Catholics and no-Catholics alike, and will be on display Saturday when Pope Francis canonizes two children whose “visions” of the Virgin Mary 100 years ago turned the sleepy farming town of Fatima into a major Catholic pilgrimage site.

Francis recently reformed the process to address financial abuses that had long tarnished the Vatican’s saintmaking machine, but the basic criteria remain.

HOW ARE SAINTS MADE?

A postulator — essentially the cheerleader spearheading the project — gathers testimony and documentation and presents the case to the Vatican’s Congregation for the Causes of Saints. If the congregation’s experts agree the candidate lived a virtuous life, the case is forwarded to the pope, who signs a decree attesting to the candidate’s “heroic virtues.”

If the postulator finds someone was miraculously healed by praying for the candidate’s intercession, and if the cure can’t be medically explained, the case is presented to the congregation as the possible miracle needed for beatification. Panels of doctors, theologians, bishops and cardinals must certify that the cure was instantaneous, complete and lasting — and was due to the intercession of the saintly candidate. If convinced, the congregation sends the case to the pope, who signs a decree saying the candidate can be beatified.

A second miracle is needed to declare the candidate a saint.

Martyrs — people killed for their faith — can be beatified without a miracle. A miracle is needed, however, for martyrs to be canonized.

THE MARTO CASE, A FIRST

The Marto siblings are the Catholic Church’s youngestever non-martyred saints.

Portuguese Cardinal Jose Saraiva Martians pushed their case through the first phase of beatification when he was in charge of the Vatican’s saint-making office. He says it was the first of its kind.

“Before we couldn’t even talk about the beatification of children in the history of the church because the principle prevailed that they didn’t yet have the skills to exercise the heroic level of Christian virtues,” Saraiva Martins said in an interview.

But Francisco and Jacinta Marto earned the designation by refusing — despite threats they would be fried in olive oil — to recant their visions. Aged 9 and 7 at the time, they held firm in their faith, and ultimately Portuguese church officials declared the apparitions authentic.

FRANCIS’ REFORMS

Francis has issued two major reforms to the multimillion dollar saint-making process after the Vatican uncovered gross abuses that were revealed in two books. The books estimated the average cost for each beatification at around 500,000 euros ($550,000), with much of the proceeds going to a few lucky people with contracts to do the time-consuming investigations into the candidates’ lives. The books found that well-financed causes sprinted ahead while poorer ones languished.

Francis last year issued new rules requiring external vigilance over individual Vatican bank accounts created for beatification and canonization causes, as well as regular budgeting and accounting to make sure the donations from the faithful are being used as intended.

The second reform concerns the miracle certification process: One new rule stipulates a potential miracle can no longer be presented for consideration if it fails to pass before the board of medical experts three times. Secrecy must be respected at all times. Medical experts can’t have any contact with the postulator. Another rule says experts can be paid only via bank transfer, no longer in cash.

BUT HASN’T FRANCIS DONE AWAY WITH MIRACLES?

In his zeal to give the faithful even more role models, Francis has on several occasions done away with the Vatican’s rules requiring two miracles.