Fertility has declined much more among nonreligious Americans than among the devout, according to a leading social scientist.

Lyman Stone of the Institute for Family Studies, says data from the National Survey of Family Growth (NSFG) from 1982 to 2019, along with data from four waves of the Demographic Intelligence Family Survey (DIFS) from 2020 to 2022, point to a widening gap in fertility rates between more religious and less religious Americans.

Among those who attend religious services every week, the fertility rate remains above the replacement rate of 2.1, while among the non-religious it has gone below 1.5.

In recent years, the fertility gap by religion has widened to unprecedented levels. But while this difference may comfort some of the faithful who hope higher fertility will ultimately yield stable membership in churches and synagogues, these hopes may be in vain. Rates of conversion into irreligion are too high, and fertility rates too low, to yield stable religious populations.