After a traumatic experience, increases as well as decreases in religious beliefs and activities have been observed. The current study investigated how the direction of the changes can be predicted and whether these changes are related to posttraumatic stress disorder. Trauma survivors (N = 293) filled in questionnaires related to traumatic experiences and religiosity. Nearly half of the sample reported changes in religious beliefs and activities as a consequence of the trauma. As hypothesized, shattered assumptions and prior religiosity interacted to predict a decrease in religious beliefs and activities. Increases in religiosity were related to the use of religion as a coping mechanism and to currently living in a religious environment. In addition, a decrease in religious beliefs was related to higher levels of posttraumatic stress disorder. The findings suggest that religiosity may play an important role in posttrauma adaptation.