This paper examines the causal effect of religious identification on political preferences, gender norms, and group behavior. Using clergy abuse scandals as exogenous variation in Catholicism, we analyze data from millions of U.S. college freshmen and county-level voting records. We find that religious de-identification leads to more progressive views on social issues and gender norms, but more conservative stances on healthcare and military spending. Overall, secularization causes a leftward shift in political orientation. Religious de-identification also reduces engagement in other group activities. As individuals disaffiliate from Catholicism, they increasingly identify with their social class, polarizing economic preferences between income groups.