Here’s the key nuance: while religious affiliation makes no difference when it comes to divorce, religious attendance does. The “Red States, Blue States” research fails to make this distinction.

The strongest evidence of the marriage-stabilizing power of religious participation comes from the National Longitudinal Study of Adolescent Health (Add Health), a federally funded, nationally representative sample of young adults. Our recent analyses of Add Health reveal that attending church regularly during young adulthood appears to significantly decrease the risk of divorce, even for those who marry relatively young…

Nominally religious young adults are in a vulnerable position: they are religious enough to be pushed into early marriage, for instance, but, lacking the social support mediated by an in-the-flesh religious congregation, they don’t reap the benefits of involvement in a religious community. Instead, religion may become a source of conflict. Like Kayla and Adam, most of the working-class, divorced individuals interviewed in the Middle America Project either reported pressure from religious relatives to marry earlier than they would have liked, or reported conflict because one spouse was not on board with the other spouse’s religious involvement.

In other words, a little bit of religion can be a bad thing for marriage.