This paper examines whether and how religion contributes to prisoner rehabilitation—conceptualized as a prosocial change in self-identity, existential belief, and character based on identity theories of criminal desistance, the “Good Lives Model” of offender rehabilitation, and the concept of human flourishing. For this study, we conducted a quasi-experimental study assessing a faith-based program, “The Prisoner's Journey” (TPJ). We hypothesized that participation in TPJ increased religiosity, which in turn contributed to rehabilitation, measured by identity transformation, a new sense of meaning and purpose in life, and virtue development. It was also hypothesized that prisoner rehabilitation enhanced emotional well-being and reduced the risk of interpersonal aggression. To test our hypotheses, we applied structural equation modeling to analyze data from 506 prisoners in Colombia and South Africa, who participated in pretest and posttest surveys. As hypothesized, we found that completion of TPJ increased religiosity, which in turn fostered motivation for identity change, the perception of meaning and purpose in life, and the virtues of forgiveness, accountability, and self-control. In addition, the increased perception of meaning and purpose in life and two virtues (forgiveness and self-control) decreased negative emotions and the risk of interpersonal aggression. The implications and limitations of our study are discussed.https://journals.sagepub.com/home/ICJhj2023Social Work and Criminolog