This article uses ethnographic data from two of Rio de Janeiro's inmate-led prison churches to examine how they function. It also highlights the structural and functional parallels of these churches with prison gangs. I argue that the gang-like characteristics of these churches are an important reason for the success of Pentecostalism inside Rio de Janeiro's penal system. The results of this research can inform future scholarly investigation and prison ministry initiatives. This article uses ethnographic data from two of Rio de Janeiro's inmate-led prison churches to examine how they function. It also highlights the structural and functional parallels of these churches with prison gangs. I argue that the gang-like characteristics of these churches are an important reason for the success of Pentecostalism inside Rio de Janeiro's penal system. The results of this research can inform future scholarly investigation and prison ministry initiatives. This article uses ethnographic data from two of Rio de Janeiro's inmate-led prison churches to examine how they function. It also highlights the structural and functional parallels of these churches with prison gangs. I argue that the gang-like characteristics of these churches are an important reason for the success of Pentecostalism inside Rio de Janeiro's penal system. The results of this research can inform future scholarly investigation and prison ministry initiatives. This article uses ethnographic data from two of Rio de Janeiro's inmate-led prison churches to examine how they function. It also highlights the structural and functional parallels of these churches with prison gangs. I argue that the gang-like characteristics of these churches are an important reason for the success of Pentecostalism inside Rio de Janeiro's penal system. The results of this research can inform future scholarly investigation and prison ministry initiatives.