An interesting survey done by Gallup-Healthways suggests that a higher sense of well-being is correlated with how religious a person is:
An analysis of more than 676,000 Gallup-Healthways Well-Being Index interviews conducted in 2011 and 2010 finds that Americans who are the most religious have the highest levels of wellbeing. The statistically significant relationship between religiousness and wellbeing holds up after controlling for numerous demographic variables.
The study theorizes that this may be because of the habits and behaviors that religions often promote are also those that promote well-being:
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 analyses have clearly shown that time spent socially and social networks themselves are positively associated with high 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, 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.
…and discourages those that may lead to unhealthy consequences:
Highly religious Americans’ healthier behaviors may have multiple causes, including for example culturally negative norms against such behaviors as smoking and alcohol consumption in various 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.
There are probably many factors at play, and one also wonders why, despite the above, religion is often such a divisive and disruptive force as well.