Church-going fell by far less for evangelicals. The Southern Baptist Convention, the largest and most influential evangelical group, shrank by a mere 11% from 2010 to 2020 despite being roiled by various scandals straight from the Old Testament. Among the 50 largest religious sects in the country, evangelicals account for six of the ten fastest-growing. Not a single mainline Protestant church gained members. But some groups grew quickly: non-denominational Christian churches recruited 9m new members over the past decade, an increase in membership of 72%. Catholics claim they gained nearly 3m members (a 5% increase) despite closing over 1,100 churches. Geographically, the states with the highest shares of Catholics and mainline Protestants have seen the biggest drop in religious adherence (see chart).

What has gone so wrong for America’s oldest churches? One answer is age. According to data from the Pew Research Centre, a think-tank, a majority of mainline Christians are over 50 and one-third are older than 65. Only about one in ten are under the age of 30. For many churches, older congregants are simply dying too quickly to be replaced by new members.

Another explanation is conversion. Pew finds that just over one-third of Americans between the ages of 30 and 39 who were brought up in Christian households no longer identify with that faith. But only 20% of young adults brought up outside the church have travelled in the opposite direction, making far more leavers than joiners. The problem has become even worse in recent years. According to Pew, in 1990 only one in ten Christian-raised adults between the ages of 30 and 34 became “switchers”. Rates have more than tripled since then.

Pew reckons that if these trends continue, the non-religious could become the dominant group in American society as soon as 2055. One concern is what the shepherds will do next. A deeper one is what happens to a wandering flock.■