Following the call to shake up the Church, thousands of young Catholics flooded the streets of Rio, chanting "this is the pope's youth!"
They waved flags from around the world -- Brazil, Australia, South Africa, the United States -- and pitched tents on the crescent-shaped beach of Copacabana for an all-night vigil and final mass with the pope to cap World Youth Day festivities.
Since his election in MarchB, history's first Latin American pope has sought to re-energize Catholics, using his Rio trip to urge young believers to spread the Gospel and "make a mess" in their dioceses.
Flanked by the Sugarloaf mountain and Christ the Redeemer statue atop a peak, the faithful reflected on the pope's message during a nine-kilometer (5.5-mile) pilgrimage to the beach.
Many agreed that the Catholic Church needs a dose of energy, lamenting that too many have lost interest in a religion that has been hurt by pedophilia scandals.
Some suggested that social media can help spread the Gospel, others said young Catholics needs to be more active, join missions and open up about their faith.
"Oh yeah! Shake it up, big time! You have to," said Adrian Antonio Flores, a 31-year-old from the US state of Minnesota who works for a website catering to young Catholics.
"We're alive, we're on fire. When people see others on fire, it's contagious," he said before a prayer with 33 other Americans. "The Church needs to say to young people, here's social media and there's a light in media."
Roque Sanchez, a 22-year-old mathematics student holding a flag of his native Mexico, said the Church "needs to adapt, use things like Facebook."
"The Church must renew itself, otherwise it will be like in the Middle Ages," he said.
While Yu-Chun Hung, a 25-year-old English teacher from Taiwan, agreed that the Church needs to adapt to a fast-moving society, she warned that social media must be used carefully.
"Young people can be easily seduced. Using social media could be bad or wrong, but it depends on how we use it. Like a gun, it can hurt people but a gun can also protect people," she said, wearing a conical straw hat.
Although many said the Church must stick to dogma, Priti Khatiwada, a 16-year-old Catholic school student from Australia, said it should consider allowing priests to marry.
Some of the sins committed by clergymen, she said, may be due to the fact that "they have been deprived of basic human necessities."
The Church has struggled with scandals that have alienated some faithful. Even Brazil, the world's biggest Catholic country, has seen its flock dwindle while Evangelical churches and secularism advance.
But Pope Francis has generated wall-to-wall news coverage of his visit.
Many pilgrims said the 76-year-old pontiff has connected with them with his charisma and tendency to break protocol to embrace people who have lined the streets to see him.
"I think he's lovely, really down to earth," Khatiwada said.
The mass of people at World Youth Day, however, has caused logistical headaches for organizers, who have come under fire over a metro breakdown and the sudden switch of venue for the vigil.
The grand finale was supposed to take place on a field west of Rio, but rain turned it into a mud pit, forcing authorities to move the events to Copacabana.
During Saturday's march, some pilgrims stood in huge lines for as long as three hours to receive a food box being distributed near a war monument. Some shouted at people trying to break in line.
"It's very chaotic," said Yolanda Chao, 48, of Vancouver, Canada.
But Chao and most pilgrims have remained upbeat despite the rain and logistical missteps.
"There are a million people so it will be hard for everything to run smoothly," said Australian student Bronte Dunne, 16. "People should understand and be patient."
And many were looking forward to spending the night on Copacabana, usually famous for curvacious women in tiny bikinis.
"God will work a miracle after we're gone," said Father Pierre Claver of Ivory Coast. "The girls in the sexy bikinis will see that the young people here today are giving another message, that Jesus is here and everywhere."