We examine aging patterns and generational trends in religion using 35 years of survey data from 420 four‐generation families and in‐depth interviews with a subset of 25 families. Results indicate the importance of three time‐related effects on religiosity: individual aging and religious development over the life course; cohort influences; and effects of historical trends in religion. Results indicate an overall aging effect with an upward drift in religious intensity and strength of beliefs over the adult lifespan, though religious attendance remains generally stable over adulthood until it drops in late life. Growth curves show that the oldest generations (G1 and G2) display a “retirement surge” in religiosity. Trajectories of change for G3s and G4s reflect both lifecycle and cohort effects. Qualitative analysis provides insight concerning the generational differences identified in the survey, suggesting two trends: (1) from older‐ to later‐born age groups, spirituality becomes increasingly decoupled from religion; (2) conceptualizations of the divine show a shift from a God who is primarily transcendent (“out there”) for the G1s to one that is more imminent and personal in the G4s.