The major problem with these studies is that they're often only done in the United States where the religious are a majority and the non-religious are a minority. This of course satifies another criteria for happiness.
In fact, a study done in the Netherlands and Denmark, where the non-religious are the majority, resulted in much, much lower differences between the two. As the study concludes:
"the question in further research should not be whether religiousness boosts happiness, but in what conditions for what people." |
There are just so many variables involved here, namely geographical, that a blanket conclusion that 'religious people are more likely to be happy' is a gross oversimplification.
A sense of community is what I would attribute as being the strongest factor for that argument. Of course, I'm talking purely out of my ass on that thought.