Sexual and reproductive health policies often confront deeply rooted religious opposition that can limit their effectiveness. This paper examines how Zambia’s 2014 Comprehensive Sexuality Education (CSE) reform interacted with the rapid expansion of non-traditional Christian churches that strongly opposed the policy. Exploiting pre-reform variation in exposure to these churches in a difference-in-differences design, we find that more-exposed areas experienced lower approval of government performance in health and education and higher civic engagement following the reform. Among adolescents, greater exposure was associated with lower contraceptive use and higher rates of teen pregnancy, despite no increase in sexual initiation. These behavioral responses are concentrated among cohorts who were of school-going age when CSE was introduced. We find no evidence that the results are driven by lower school participation, fewer CSE-trained teachers, or lower HIV-related knowledge. Together, the findings show that the effects of nationally uniform sexual and reproductive health policies can depend on the local religious environments in which they are implemented.