Both women and men in "highly religious" couples- i.e. regular attendees- reported significantly greater satisfaction in their relationship than did both the other groups, with liberal, secular couples running a close second.
The difference was especially notable for women: women in "highly religious" relationships were about 50% more likely to report that they are "strongly satisfied" with their sexual relationship than their secular and less religious counterparts.
"For women, then, there is J-Curve in relationship quality, with secular progressive women doing comparatively well, women in the middle doing less well,and highly religious women reporting the highest quality relationships," the authors wrote.
"Among men, highly religious traditional men were found to be significantly higher in relationship quality than men in shared secular progressive and less religious progressive relationships."
In addition, women in highly religious couples were most likely to report that she and her spouse practice joint decision-making in their relationship.
The researchers assigned a "relationship quality" score in order to compare different religious affiliations in their sample, with a higher score representing greater overall satisfaction. Catholic couples sampled reported an overall score of 15.83, which is equal to the score reported by Muslims and slightly higher than the score for nonreligious couples.
Protestants and Latter-Day Saints lead the table with scores of 16.36 and 17.24, respectively.
"In listening to the happiest secular progressive wives and their religiously conservative counterparts, we noticed something they share in common: devoted family men," the authors wrote in a New York Times op-ed accompanying the release of the study.
"Both feminism and faith give family men a clear code: They are supposed to play a big role in their kids' lives. Devoted dads are de rigueur in these two communities. And it shows: Both culturally progressive and religiously conservative fathers report high levels of paternal engagement."
Relationship to domestic violence
The study found that "women in highly religious couples are neither more nor less likely to be victims of IPV [Intimate Partner Violence], and men in highly religious couples are neither more nor less likely to be perpetrators of IPV."
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Domestic violence- including hysical abuse, sexual abuse, emotional abuse, and controlling behaviors- is neither more nor less prevalent among religious couples than among nonreligious ones, they concluded. Infidelity was highest among men in mixed or less religious couples than any other, however.
"Although women in less/mixed religious couples have a 26% probability of ever having been the victim of violence in their relationship, compared to a 21% probability for women in highly religious couples, and a 23% probability for women in shared secular couples, none of these differences are statistically significant," the authors note.
Religion's and fertility
In terms of fertility, the study found that people aged 18-49, who "attend religious services regularly have 0.27 more children than those who never, or practically never, attend," and thus "those with egalitarian gender role attitudes are less likely to be married and have slightly fewer children."
The authors also examine a theory, which they say is common among academics in their field, that a shift in many societies toward greater gender equality, which often takes the form of married women continuing to seek work outside the home, may actually help to raise the fertility rate back to replacement levels in countries where it is especially low.
"In modern societies where women typically have high demands in the public (paid work) sphere of their lives, support from partners is necessary to make bearing two children commonplace," the authors explained.