Neo-Pentecostalism is among the fastest-growing religious movements in the world. We study how exposure to it shapes individual dispositions and economic behavior using a randomized controlled trial in Kisumu, Kenya. Participants were randomly assigned invitations to workshops hosted by Pentecostal churches, workshops hosted by mainline Christian churches, or neither, followed by surveys and choice experiments to elicit incentive-compatible economic behavior both one and twenty months afterward. Assignment to either type of church reduces contributions to a communal entrepreneurship fund by 16 percent relative to the control. Assignment to Pentecostal churches also reduces reported financial transfers to family and friends and increases men's willingness to make interest-bearing investments in the experimental game. Pentecostal assignment further lowers self-reported grit and self-control, effects that persisted twenty months later and are consistent with changing evaluative standards regarding personal success. By twenty months, treated respondents were less likely to identify as Pentecostal, with exploratory evidence suggesting disillusionment when the material promises of its associated prosperity theology failed to emerge. Our findings provide causal evidence that religious participation can reshape informal obligations and economic behavior, and that the rapid growth of Pentecostalism may further amplify such effects with economically meaningful implications for investment behavior.