The study defined "highly religious" people as those for whom "religion is an important part of daily life and church/synagogue/mosque attendance occurs at least every week or almost every week." There were two other groups in the study-- the moderately religious and the nonreligious. There was a "statistically significant relationship between religiousness and wellbeing" and this difference "holds up after controlling for numerous demographic variables." This level of "well-being" was caused by things like "healthy behaviors, life evaluation, work environment perceptions, and emotional health."
The article can be found at the Gallop website. It not only gives the results study, but there is also an overview of how the study was conducted. Here is the section of the article subtitled "Implications"
Americans who are very religious have higher wellbeing than those who are less religious, a relationship that holds even after controlling for several related demographic and geographic variables.By the way, there was no statistically significant difference between the well-being of those who were only moderately religious and those who are totally nonreligious. So if you are going to be religious, you might as well go whole hog and do it right. This will also promote your spiritual well-being as well.
This study does not allow for a precise determination of why this might be the case. It is possible that Americans who have higher wellbeing may be more likely to choose to be religious than those with lower wellbeing. It is also possible that some third variable could be driving certain segments of the U.S. population to be more religious and to have higher wellbeing.
It is also possible that the relationship is straightforward, that something about religiosity, defined as a personal importance placed on religion and frequent religious service attendance, in turn leads to a higher level of personal wellbeing. Religious service attendance promotes social interaction and friendship with others, and Gallup analysis has clearly shown that time spent socially and social networks themselves are positively associated with wellbeing. Religion generally involves more meditative states and faith in a higher power, both of which have been widely used as methods to lower stress, reduce depression, and promote happiness. Religion provides mechanisms for coping with setbacks and life's problems, which in turn may reduce stress, worry, and anger. Many religions, including Christianity, which is by far the dominant religion in the U.S., embody tenets of positive relationships with one's neighbors and charitable acts, which may lead to a more positive mental outlook.
Highly religious Americans' healthier behaviors may have multiple causes, including for example culturally negative norms against such behaviors as smoking and alcohol consumption in a number of religions. It may also be possible that the lower emotional wellbeing of less religious Americans puts them in a state in which they are more susceptible to non-healthy behaviors.