Islamic radicalization is one of the main correlates of violent conflict in the world today with important implications in Sub-Saharan Africa. We ask whether Islamic radicalization and related violence can be countered through campaigning by local religious organizations. We follow a campaign against violence in the province of Cabo Delgado, Mozambique, a setting that has seen a recent violent insurgency. The campaign focused on the key message that religion is not violent. It was broadcasted through community radios and individual voice messages sent to cell phones. We measure the impact of the campaign on violent events, various behavioral measures including anti-social behavior and trust, as well as survey attitudes. We find that the campaign decreased the incidence of violent events in the province, mediated through an increase in trust. Our evidence suggests that involving local religious organizations can be central to counter violent Islamic radicalization.