From 2000 onward for contemporary relevance, among women aged 40 or older for completed fertility, and restricted to non-Hispanic whites to avoid racial confounding, we have TFRs by educational attainment and religious service attendance:
Religiosity is a strong correlate with fertility. Nothing quite trumps the inverse correlation fecundity has with female educational attainment, a robust relationship holds both within countries and between them, but religiosity comes close. To concisely extract that from the preceding graph, consider that with the exception of high school dropouts, women who do not attend religious services are below replacement across the board. In contrast, women who regularly attend services are, with the exception of post-graduates, all above replacement.
If you didn’t see how free college and fighting climate change are closely related, now you should.
Parenthetically, “infrequent attendance” = between never attending and attending once per year; “occasional attendance” = between several times a year and several multiple times per month but not weekly; “regular attendance” = between nearly every week and multiple times per week.
GSS variables used: YEAR(2000-2018), AGE(40-89), SEX(2), RACECEN1(1), HISPANIC(1), CHILDS, DEGREE