“Mainline” churches are emptying. The political effects could be huge.

In April, the New York Times’s Ross Douthat wrote a column arguing — appropriately for a Sunday opinion piece — that liberals need to go to church. More specifically, he argued: “The wider experience of American politics suggests that as liberalism de-churches it struggles to find a nontransactional organizing principle, a persuasive language of the common good.”

For a theologically confessional Lutheran and politically conservative Republican like me, this is an interesting suggestion. How much of the cultural and political change we have observed in the past 20 years can be explained by the quiet death of the “mainlines”?

For readers not familiar with Christian denominational classifications, “mainline” is the term that students of American religious life use to refer to more theologically or politically liberal white-majority churches. Since Sunday morning remains America’s most segregated hour, experts separate “historically black Protestant” churches into their own group, and then divide the white churches into various segments.

Mainline churches today remain diverse but tend to share a cluster of overlapping values: They may endorse same-sex marriage in the church, hold more lenient views on extramarital sex, confess less exclusivist views of eternal salvation, and focus more political efforts toward Christian social relief rather than Christian moral teachings; many mainlines have formal fellowship agreements with one another.

These churches are dying off at a very quick pace. Within the Presbyterian family, the “mainline” Presbyterian Church (USA) is shrinking while the “evangelical” Presbyterian Church of America is growing. Within the Lutheran family, the “mainline” Evangelical Lutheran Church in America (yes, the “Evangelical Lutherans” are mainline, not evangelical; one of many absurdities in religious verbiage) is shrinking rapidly while “evangelical” Wisconsin or Missouri Synod Lutherans are either holding steady or shrinking slowly. Within the Methodist family, “mainline” United Methodists are shrinking while “evangelical” Free Methodists are holding steady. Both sides of the Baptist family tree are shrinking, but the mainline side is shrinking faster.

Much of this is driven by natural population aging, given that the evangelical churches tend to attract families with more kids and have been somewhat more popular with immigrants than the mainline churches. But much of it has also been driven by conversion: In 2014, the Pew Research Center found that 1.7 peopled converted away from mainline Protestant groups for every one convert in, while evangelical Protestants had 1.2 people convert in for every leaver.

Many people may think these shifts are only of interest to church workers or the devout. But Douthat suggested, and I will elaborate on the view, that liberalism itself might be put on a stronger intellectual and social footing if it reembraced churchgoing. (Douthat also argued that going to church will ultimately help liberals and progressives attain what we might call eudaimonia; I won’t address that in depth here but, as a Lutheran I must take issue and suggest that, actually, while being a Christian is swell and all, “you will have troubles.” But I digress…)