Previous studies have suggested that specific features of religion such as religious denomination and level of religiosity might influence the severity of obsessive- compulsive disorder (OCD) and the occurrence of obsessive- compulsive (OC) cognitions, whereas others could not confirm these findings. The purpose of this study was to elucidate the relation between religion, OCD, and the occurrence of OC cognitions in a Dutch sample of OCD patients. Data were drawn from the baseline assessment of the Netherlands Obsessive Compulsive Disorder Association (NOCDA; Schuurmans et al., 2012) study, which is an ongoing, multicenter, 6-year, longitudinal naturalistic cohort study examining the course of OCD. Participants were 377 outpatients, age 18 years and over, with a lifetime diagnosis of OCD. Neither being religious nor religiosity critically influenced the severity of OCD or the occurrence of OC cognitions. Roman Catholic patients scored significantly higher on anxiety and depression than nonreligious patients, and Roman Catholic patients endorsed significantly more OC cognitions than nonreligious and Protestant patients. These ratings of OC cognitions were not mediated by religious denomination or level of religiosity, but by severity of anxiety and depression, as well as age. The relationship between religious denomination, level of religiosity, and clinical aspects of OCD, which have been described before in the literature, may be spurious and mediated by comorbid psychiatric symptoms, such as anxiety and depression.