Pentecostal Christianity is flourishing inside the prisons of Rio de Janeiro. To find out why, Andrew Johnson dug deep into the prisons themselves. He began by spending two weeks living in a Brazilian prison as if he were an inmate: sleeping in the same cells as the inmates, eating the same food, and participating in the men's daily routines as if he were incarcerated. And he returned many times afterward to observe prison churches' worship services, which were led by inmates who had been voted into positions of leadership by their fellow prisoners. He accompanied Pentecostal volunteers when they visited cells that were controlled by Rio's most dominant criminal gang to lead worship services, provide health care, and deliver other social services to the inmates. Why does this faith resonate so profoundly with the incarcerated? Pentecostalism, argues Johnson, is the 'faith of the killable people' and offers ex-criminals and gang members the opportunity to positively reinvent their public personas. If I Give My Soul provides a deeply personal look at the relationship between the margins of Brazilian society and the Pentecostal faith, both behind bars and in the favelas, Rio de Janeiro's peripheral neighborhoods. Based on his intimate relationships with the figures in this book, Johnson makes a passionate case that Pentecostal practice behind bars is an act of political radicalism as much as a spiritual experience.