Despite increased research on factors that predict engagement in nonsuicidal self-injury (NSSI), one factor that has been neglected is spirituality/religiosity. While some researchers suggest that spiritual/religious beliefs and practice may protect against aversive mental health outcomes, it also is possible that certain aspects of spirituality/religiosity – specifically doubt and questioning – may be distressing. In this study, we examined whether multiple dimensions of spirituality/religiosity, including the often-overlooked experience of doubt/questioning, were associated with engagement in NSSI among university students over time. Participants included 1,132 (70.5% female) first-year undergraduate students (Mean age=19.06, SD=1.05) from a Canadian university who were surveyed first in their freshman year, and again one year later. Auto-regressive cross-lagged analyses revealed a bidirectional relation between doubt/questioning and NSSI, where higher doubt/questioning predicted increased NSSI over time (after controlling for baseline depressive symptoms), and vice versa. There were no longitudinal associations between general spirituality/religiosity (i.e., general beliefs/practice) and NSSI. Our findings suggest questioning and doubt may be distressing for some individuals, and predict increased risk for NSSI as a form of coping. Further, higher NSSI may predict increases in questioning/doubt over time. However, the hypothesis that general spirituality/religiosity may protect against NSSI, was not supported.