Secularization—Still Going Strong? What Remains When Cross-sectional Differences Are Eliminated from a Longitudinal Analysis

The tendency of decreasing religiosity is explained by the theory of secularization through differentiation and pluralization. Using the ess 2002–2016, the impacts of both on church attendance and self-ascribed religiosity are tested, controlling for determinants of religiosity—that is, for belonging (cohort and denomination) and choice (education, urban residence, marriage, parenthood, and employment)—with multi-level models separating between- from within-country effects. Without controls, time negatively affects religiosity: there is a secularization tendency. But controlling for cohort and denomination annihilates this effect and strongly reduces individual-level as well as country-level error variances. Effects of belonging are stronger than those of choice, cohort succession has a negative effect, and religiosity differs between denominations. Differentiation and pluralization have only a few effects between countries and only one within countries such that secularization theory is not confirmed.