Certainty:
Previous studies demonstrating a positive relationship between religiosity and mental health have sampled from a highly religious general population with little differentiation between weak religiosity and non-religiosity. Church members are typically compared with non-religious unaffiliated individuals, thus confounding belief with group effects (e.g. social support). The present study examined mental well-being, utilising the full range of certainty of belief or non-belief in God. In the first study, we compared church and secular group members on measures of life satisfaction and emotional stability. The second study used a large survey of the non-religious. A curvilinear relationship was found such that those with higher belief certainty (both confidently religious and atheists) have greater well-being relative to those with low certainty (unsure and agnostics). Multiple regressions controlling for social and demographic variables reduced, but did not eliminate this curvilinear relationship. Mechanisms of well-being may involve a confident worldview rather than religious beliefs themselves.
Source: “Mental well-being in the religious and the non-religious: evidence for a curvilinear relationship” from Mental Health, Religion & Culture
What can we all learn from religion — whether we believe or not?