Both religion and egalitarianism have something to offer those seeking a happy marriage in a world of shifting mores—though religion leads to more children—a new report on international perspectives on marital happiness shows.

The report, a joint project of the Institute for Family Studies and the Wheatley Institution, uses data from two surveys of respondents in eleven countries: Argentina, Australia, Chile, Canada, Colombia, France, Ireland, Mexico, Peru, the United Kingdom, and the United States. The authors set out to examine the now standard bromide that progressive, secular social values lead to happier marriages.

As study authors W. Bradford Wilcox, Jason S. Carroll, and Laurie DeRose wrote in the New York Times, the recipe for a happy marriage is either being religious or being egalitarian—those stuck in the middle are consistently the worst off.

To reach this result, the study's authors looked at roughly 5,000 couples surveyed in the Global Family and Gender Survey (GFGS). Based on frequency of religious attendance, these couples were classified as either secular, religious, or mixed. What the survey data show is that high religious couples report higher rates of marital and sexual satisfaction than their mixed or secular peers.

To nuance this analysis, the authors then looked at the relationship between religious attendance, relationship satisfaction, and sentiments about gender equality. Specifically, they broke down respondents by their (dis)agreement with the statement, "it is usually better for everyone involved if the father takes the lead in working outside the home and the mother takes the lead in caring for the home and family."

Combining the two categories generated by yes/no answers to this question with the three categories, the authors find what they characterize as a "j-curve": the more progressive, irreligious couples are happier than the mixed traditional and progressive couples, but the religious couples are the happiest of all. In other words, an irreligious, non-progressive couple is less happy than a progressive one, but both are less happy than a religious couple.

This dichotomy between the religious traditionalist and the progressive egalitarian persists across other findings in the report. For example, both are less likely to engage in intimate partner violence, and both are more likely to share decision-making responsibilities.

The study's authors are quick to emphasize that there is not necessarily a causal relationship between religious or progressive values, and marital happiness, only a correlation. Nonetheless, these findings suggest two different models for how to run a successful, happy marriage. Either one practices a gender egalitarian model, where work is shared equally; or one relies upon the social capital and support of a religious community to encourage a well-balanced and happy marriage.

Those who lose out, in terms of marital happiness, are those who neither share labor within the marriage nor with a larger community. This is the group of Americans whose lives Washington Examiner editor Timothy P. Carney recently covered in his book Alienated America. Carney argues that left-behind Americans—like the millions who put Donald Trump in the White House—suffer from a lack of social capital, brought on by a decline of religious community.

There is one factor where religious couples beat egalitarian couples: fertility. The study's authors find that the fertility gap between highly religious and irreligious couples has grown over the past two decades, from an additional 0.24 kids to an additional 0.27 kids on average. Across countries with below-replacement fertility rates, indicators like frequency of religious attendance were clearly related to fertility.

As such, while progressive values might be a recipe for a happier marriage, they are less likely to lead to a rising fertility rate. Contra claims that feminism is the new pro-natalism, religion still seems the way to go if you want to have more kids.