Does Religion Make Us Nice?

From Slate, an interesting essay on the effect of religion.  From the opening:

Arguments about the merits of religions are often battled out with reference to history, by comparing the sins of theists and atheists. (I see your Crusades and raise you Stalin!) But a more promising approach is to look at empirical research that directly addresses the effects of religion on how people behave.

Studies show that religious Americans tend to be happier and more generous than their secular counterparts.  But what explains the relatively happy and godless Scandinavians?  The author suggests that religion's positive effect is more about community than belief:

The Danes and the Swedes, despite being godless, have strong communities. In fact, Zuckerman points out that most Danes and Swedes identify themselves as Christian. They get married in church, have their babies baptized, give some of their income to the church, and feel attached to their religious community—they just don't believe in God. Zuckerman suggests that Scandinavian Christians are a lot like American Jews, who are also highly secularized in belief and practice, have strong communal feelings, and tend to be well-behaved.

American atheists, by contrast, are often left out of community life. The studies that Brooks cites in Gross National Happiness, which find that the religious are happier and more generous then the secular, do not define religious and secular in terms of belief. They define it in terms of religious attendance. It is not hard to see how being left out of one of the dominant modes of American togetherness can have a corrosive effect on morality. As P.Z. Myers, the biologist and prominent atheist, puts it, "[S]cattered individuals who are excluded from communities do not receive the benefits of community, nor do they feel willing to contribute to the communities that exclude them."