Despite that the majority of the studies concluded that spirituality was associated with higher well-being, no definitive conclusions on this relationship can be drawn due to major methodological shortcomings of these studies. Longitudinal research utilizing spirituality and well-being measures that do not overlap in content is recommended.

The objective of this meta-analysis was to determine the longitudinal positive effect of religion or spirituality (R/S) on mental health. We summarized 48 longitudinal studies (59 independent samples) using a random effects model. Mental health was operationalized as a continuous and a dichotomous distress measure, life satisfaction, well-being, and quality of life. R/S included participation in public and private religious activities, support from church members, importance of religion, intrinsic religiousness, positive religious coping, meaningfulness, and composite measures. The meta-analysis yielded a significant, but small overall effect size of r = .08 (95% CI: 0.06 to 0.10). Of eight R/S predictors that were distinguished, only participation in public religious activities and importance of religion were significantly related to mental health (r = .08 and r = .09, respectively; 95% CI: 0.04 to 0.11 and 0.05 to 0.12, respectively). In conclusion, there is evidence for a positive effect of R/S on mental health, but this effect is small.

It has been suggested that spirituality is associated with higher well-being, because it offers social support, improves the relationship with the partner, provides meaning, and reduces self-focus and worry. We performed a qualitative study among ten people with cancer, using the Consensual Qualitative Research method for the analysis of semi-structured interviews. Support was found for the mechanisms of meaning provision and of reduction of self-focus and worries. Participants also mentioned emotion-focused roles of spirituality: Feeling supported by a transcendental confidant, the expression of negative emotions (in prayer), acceptance, allowing feelings of misery, and viewing problems from a distance. There was no mention of a contribution of spirituality to adjustment through improved social support per se or a higher quality of the relationship with the partner. The results of the present study indicate that the role of spirituality in emotion regulation deserves attention in understanding how spirituality helps cancer patients to adjust to their disease.

Spirituality may help people to maintain a high level of well-being despite adversity, but several studies that claim to support this statement have used spirituality scales and outcome measures that have overlapping content. This practice seems to be widespread: In an exploratory survey of eight well-cited journals we found that 26 of 58 studies used a spirituality scale that contains 25% or more of well-being items to examine whether spirituality predicts well-being or distress. These spirituality questionnaires would be more appropriate for use as indicators of the domain of quality of life called spiritual well-being. We urge researchers to only use spirituality questionnaires of which less than 25% of the items refer to emotional well-beingsuch as the SWB Questionnaire or the Spiritual Attitude and Involvement List-when investigating the causal relationship between spirituality and emotional well-being.