The dark room with skulls painted on the walls where a dozen people are sitting in a semicircle looks like anything but a church.

But when a long-haired man starts strumming his electric guitar, another church member, Rogerio Santos, picks up a Bible.

As Santos - wearing a black leather jacket with rock band pins - starts praying, the others break into song.

This is a typical day at Metanoia church - named after the Greek word meaning "change in one's life resulting from penitence or spiritual conversion" - in the Mare slum of Brazil's second-largest city, Rio de Janeiro.

"There is a very great need for spirituality in Mare," says Santos, 47, who has belonged to Metanoia for half his life.

The church, he says, combines his two passions: "Music and religion."

The dilapidated church looks like an underground club for hard rock, with graffiti, heavy metal posters and famous album covers covering its walls. Drum sets and loudspeakers can be seen in the back of the room. A closer look reveals crosses hanging from the ceiling.

"Jesus is the lord of the underground," a slogan reads. "Jesus won," says another, which has been placed inside an imitation coffin leaning against a wall.

Enok Galvao de Lima, the pastor who established Metanoia 27 years ago, sees no contradiction between the church's heavy metal setting and its Christian teachings.

"God created music and art. The devil did not create anything. One can go and make use of this culture," the affable 54-year-old says.

Metanoia's combination of rock and religion reflects the versatility of the evangelical churches that are mushrooming in Latin America, traditionally one of the strongest bastions of Roman Catholicism.

Only 59 percent of Latin Americans identified themselves as Catholics in 2017, down from 80 percent in 1995, according to pollster Latinobarometro. Nearly 20 percent said they belonged to evangelical churches.

Child sex abuse scandals involving priests in countries such as Chile have undermined trust in the Catholic Church, which many also see as overly rigid and dogmatic.

Pentecostal evangelical preachers "tend to sound more like their congregants. They are often unfettered and they speak to their flock in the same way that people in Latin America speak to each other," Andrew Chesnut, professor of religious studies at Virginia Commonwealth University, was quoted by Pew Research Center as saying.

"They also tend to look like their congregants. So in Guatemala, many preachers are Mayan, and in Brazil they are Afro-Brazilian. By contrast, in the Catholic Church, most priests are part of the elite. They are either white or mestizo [mixed-race] and many are actually from Europe," he added.

Evangelical churches have meanwhile been gaining influence in politics. Guatemalan President Jimmy Morales is an evangelical Christian, while in Costa Rica, evangelical preacher Fabricio Alvarado came close to winning presidential elections in April.

Chile's Sebastian Pinera was elected president with the backing of evangelical churches in December, while Rio de Janeiro's evangelical Mayor Marcelo Crivella has sparked controversy with his conservative views.

Metanoia is not the only evangelical church in Mare, one of the poorest and most violent areas of Rio de Janeiro. At least six other churches stand on nearby streets, including the Assembleia de Deus (God's Assembly), one of the most influential in Brazil.

Metanoia does not comment on politics, but instead wants to be a haven for the poor. "We open a space for people who are rejected elsewhere," says church member Everton Rodrigues, 34.

Others are drawn to the "rock church" because of the music.

"It's the cultural offer that drew my attention," Rodrigues' partner, Taina Domingues, said. "I feel comfortable here," adds the 30-year-old teacher, who has been coming to Metanoia for 13 years.

The church's weekly Sunday night services, which usually bring together more than 30 people, may feature professional rock bands.

Pastor Galvao de Lima does not play an instrument, but he has made his artistic contribution to his church by painting crosses, graffiti and Gothic drawings on the walls.

The church is the only one of its kind in Rio, according to the pastor. But churches that include "Christian rock" in their services have sprung up in other large Brazilian cities, in the United States and Europe.

"The language of rock reaches a lot of people," Galvao de Lima says.