Sexual and reproductive health policies often confront deeply rooted religious opposition that can limit their effectiveness. We study Zambia’s 2014 Comprehensive Sexuality Education reform and its interaction with non-traditional Christian churches that opposed it. Using pre-reform variation in church exposure, we find lower contraceptive use and higher teen pregnancy among adolescents in more-exposed areas after the reform, persisting through 2024. We find no evidence of lower school participation or lower measured HIV-related knowledge in more-exposed areas. More-exposed areas also showed lower approval of government performance and greater civic engagement, consistent with broader political backlash.