Individuals in late adulthood are often confronted with difficulties and challenges that elicit existential questions and doubts, including religious doubts. Although research has shown that unresolved religious doubts increase the risk for depression, it remains unclear how they are related to each other in late adulthood and which mechanisms are underlying this relationship. Therefore, in a longitudinal study of 329 older adults aged 65-99 and living in a nursing home, the relation between religious doubt and depressive symptoms was explored as (...) well as the mediation effect of rumination on this relationship. The results confirmed the relation between religious doubt and the experience of depressive symptoms, with a bidirectional influence over time. However, the findings indicated that this reciprocal relationship was not mediated by rumination. The study highlights the importance of identifying older adults who experience religious doubt and who are at risk for or suffer from depressive symptoms. (shrink)