VATICAN CITY — This Sunday, Rome, a city of nearly 3 million mostly sane people, will tilt into complete chaos as two dead popes are elevated to sainthood in the presence of two live popes at a lavish ceremony in St. Peter’s square. A fleck of skin, a vial of blood and three miracles will be the central features of the double-barreled canonization ceremony, which is expected to last about two hours and draw as many as a million people to an area with a capacity for 250,000.

The event is the first of its kind. Two popes have never been canonized together, not to mention the odd fact that two popes have never actually been alive together, making the event a sort of quadruple pope-a-palooza. Reigning Pope Francis will preside over the ceremony, and retired Emeritus Pope Benedict XVI is expected to make an appearance as well. Karol Wojtyla from Poland, who was Pope John Paul II from 1978 to 2005, and Angelo Giuseppe Roncalli from Italy, who was Pope John XXIII from 1958 to 1963, will then be bona fide saints, making them easier to pray to, among other things, and, according to Catholic teachings, offering a guarantee that they are both securely in heaven, should anyone have been concerned.

John Paul II is interred in the crypt under St. Peter’s basilica, and John XXIII, whose body is somewhat odd and eerily completely preserved in a glass coffin, is in the upper church in a side apse. After the ceremony, revelers are expected to pray at their tombs. When parsed down into cold hard facts, the half-day event, which will cost the city of Rome around $7 million, may sound a little frivolous, but just ask any of those who have made the trip and they’ll try to convince you that what may seem like a leap of faith is actually part of being a believer. “Sometimes when everyone around you believes in something, it rubs off on you,” Johann Schulz from Germany told The Daily Beast in St. Peter’s Square on Friday. “I think a lot of us who came here for this need to believe in miracles and saints. Otherwise things look pretty grim.”

Even with the pauper pope Francis, who has said he wants a poor church for the poor, the ceremony promises to be very much a classic Vatican show. Gigantic tapestries of the two pope saints are already hanging from St. Peter’s basilica, and the city is strung with yellow police tape cordoning off a “red zone” that not even a World Cup soccer win would merit. Many of the Catholic Church’s elite cardinals from all over the world— known as the princes of the church—will be in attendance, dressed in their formal flowing gown-like cassocks and seated in gilded golden chairs carefully lined up in St. Peter’s square for the big event. They, along with more than 60 high level delegations, including 19 heads of state and 24 heads of government, will pay homage to relics—a sliver of skin sliced from John XXIII when he was exhumed in 2000, and a vial of blood from John Paul II taken when he died in 2005, which will be prominently displayed at the ceremony to represent the saints in waiting.

According to the 140-page program for the event (PDF) released by the Holy See press office, Catholics at the ceremony will even get a plenary indulgence, a Godly forgiveness for certain confessed sins that can be used in this life, the next life or in purgatory. The indulgence, however, does not apply to sins that have not yet been committed.

The men are being made saints because of their obvious holiness, and because they are both responsible for medical miracles. The “miraclees” which include two recipients of John Paul II’s miracles and a nun who witnessed John XXIII’s divine intercession, will be there too. Francis opted to waive the requisite second miracle for John XXIII usually needed for non-martyrs to reach sainthood. Popes can do what they want, it would seem.

John XXIII’s solitary miracle worker will be a Sister Adele Labianca, the nun who witnessed the inexplicable healing of Sister Caterina Capitani, a Neapolitan nun who had endured 14 surgeries for a gastric hemorrhage. The sick sister was healed after relics from John XXIII were placed on the fistula on her abdomen. After that, Sister Caterina apparently saw a vision of John XXIII in her sickroom as she lay dying, and the papal ghost told her to get up, that she was healed. “I’m hungry, I want to eat,” she kept on saying, despite the fact that all she ate would just come out of the fistula in her abdomen. She carried on saying: Pope John told me, the wound is healed,” Sister Adele explained at a press briefing on Thursday. Multiple doctors agreed that there was no medical explanation of her healing. She died in 2010 of natural causes.

John Paul II’s first miracle was the apparent healing of Sister Marie Simon-Pierre, a French nun who suffered from Parkinson’s disease until her devout prayer cured her. Simon-Pierre’s testimony featured large at John Paul II’s beatification ceremony in 2011, an event which spawned his second miracle.

Floribeth Mora Diaz, a mother of four from Costa Rica, was suffering a brain aneurysm for which her doctors had given her less than a month to live when she watched the beatification ceremony of John Paul II on TV from the sofa in her living room. She had fallen asleep holding a magazine with John Paul II’s picture and during her half-sleep, the image in the magazine reached out to her and asked her what she was doing lying around, she told reporters at a Vatican briefing on Thursday. “When I woke up in the morning, I looked at the magazine cover which showed Pope Wojtyla with his arms outstretched,” she said. “I felt a deep sense of healing. I heard his voice say to me, ‘Get up and don’t be afraid.’ I went to my husband in the kitchen and told him I was cured. I realized little by little the illness had been taken away.”

When news of her miraculous healing reached the Vatican, she says she was rushed to Rome and examined in a church-affiliated hospital where she was checked in under an assumed name and told to pose as a “Costa Rican tourist who fell ill” if anyone asked. When doctors could not explain how she had survived the aneurysm after multiple tests, she was deemed “miraculously healed by the intercession of John Paul II.”

While no one doubts that Diaz is healed, surviving brain aneurysms is not exactly miraculous. According to the Brain Aneurysm Foundation the mortality rate is around 40 percent. “I believe a lot more in the divine intervention of the neurosurgeons at Roosevelt hospital in New York, who saved my life,” says Deidre Depke, the former editor of The Daily Beast who suffered two brain aneurysms last October. “It’s not the kind of event from which you can get up, get moving and be cured.”

Despite the palpable buzz in Rome, not everyone is looking forward to Sunday’s love fest for the two popes. Survivors of sexual abuse by Catholic priests held their own briefing in Rome on Friday, against a backdrop of the photos of young children who were sexually abused during the time John Paul II was pontiff. “We were abused because John Paul II didn’t act,” Nicky Davis, a spokesperson for the Survivors Network of Those Abused By Priests known as SNAP told reporters. “We don’t’ believe it is saintly behavior to allow child abuse to continue for 27 years.”

The group, which has 18,000 members from 79 countries, says canonizing John Paul II is like “pouring salt into an open wound.” They say there is ample proof and documentation that John Paul II turned a blind eye to hundreds, if not thousands, of reports of abusive priests, and chose not to act. “We will never know what it was like not being raped,” said Barbara Blaine, president of SNAP, and for that reason alone, John Paul II should not be elevated to sainthood. The group will hold a candlelight vigil ahead of the canonization “for all those who lost their innocence during John Paul II’s reign.”

In a freak accident on Thursday, a gigantic crucifix dedicated to John Paul II collapsed and crushed a 21-year-old man near the northern city of Brescia. The man, identified as Marco Gusmini, died as he posed for a photo at the exact moment when the 100-foot-high cross snapped and fell on him. In what the Italian press has reported as an even more dramatic twist in the accident, Gusmini reportedly lived on a street named after Pope John XXIII. With all the talk of miracles, relics and saints, one might also look at omens, too, ahead of Sunday’s grand event.