After setting off from Rome this May on his first trip to Latin America, the world's most Roman Catholic region, Pope Benedict XVI made a top concern clear: These are "difficult times for the church," he told hundreds of bishops in Brazil, amid "aggressive proselytizing" by born-again Protestant congregations.
The times are particularly difficult in Brazil, which has seen a dramatic decline in Catholicism in urban areas, says Timothy Shah, adjunct senior fellow for religion and foreign policy at the Council on Foreign Relations in Washington.
It is also a fascinating time, he says. Brazil can now claim to be both the world's largest Catholic country and one of the largest Pentecostal nations, he notes.
But proselytism alone cannot account for one of religion's most dramatic demographic shifts: The number of Protestants increased from 6.6 percent of the Brazilian population in 1980 to 15.4 percent 20 years later.
The Pentecostal movement began here in the early 20th century, with an Italian missionary establishing the first Pentecostal church in 1910 in São Paulo, according to the Washington-based Pew Research Center.
Subsequent waves followed, beginning in the 1950s and '60s.
In the past two decades, Pentecostals have gone mainstream – with television stations and political candidates.
Brazil's religious landscape has since changed more than most Latin American countries.
John Burdick, an associate professor of anthropology at Syracuse University in New York, explains that non-Catholic religions tend to take root in places without a strong presence of Catholic institutions, which have had a near monopoly on Latin America since it was colonized.
Brazil has a particularly low ratio of priests to parishioners. The Getulio Vargas Foundation in Rio de Janeiro released a report upon the pope's arrival in May showing four Protestant ministers in Brazil for every Catholic priest.
In favelas, or shantytowns, throughout Rio de Janeiro, there's always a small Pentecostal church within walking distance.
Sometimes there is only one Catholic church in a favela.
In rural areas, says Mr. Burdick, it is not uncommon for a priest to appear just once a month. "The more densely present you have Catholic institutions in rural areas or urban areas ... the more you can 'resist' Protestantism," he says.
Brazil also has one of the world's greatest disparities between rich and poor and is marked by a violent urban culture. Pentecostal churches have been particularly appealing to those in need of the solutions to the problems provoked by both.
It is what David Smilde, in his new book "Reason to Believe," calls cultural agency, a way that poor Latin Americans can gain control over their immediate social contexts.
Drug and gang violence is overwhelmingly perpetrated by men, but women are victimized every day: they cover for their sons and boyfriends, they witness daylight shootouts, they have just as much at stake.
That was evident on a recent day during a skit enacted by Pentecostals at the Assembly of God New Zion church in Rio de Janeiro.
The play opened with "gunmen" storming into the church and Maria Aparecida de Carvalho burst into tears. She thought it was real.
"I live here and see a lot of these things," she says later, nervously folding a handkerchief back and forth in her hands.
The "play," which church members perform for other congregations and schools around Rio, involves the story of a drug dealer who can't come up with the money to give his bosses and is about to be executed. In Mangueira, there's nothing fictional about the plotline.
This church, Ms. de Carvalho says, is her only haven, and her faith, her body of armor.
Pentecostals often walk around with their Bibles in their hands. They do it out of faith, but it's seen as a preventive measure too, their own antidote to violence. "[Pentecostalism] provides people with a way of navigating a crime-filled context," says Mr. Smilde.