Ross Douthat writes:

The relative stability of the Gallup data fits with analysis offered by the sociologists Landon Schnabel and Sean Bock in a 2017 paper, “The Persistent and Exceptional Intensity of American Religion.” Drawing on the General Social Survey, they argued that the recent decline of institutional religion is entirely a function of the formerly weakly affiliated ceasing to identify with religious bodies entirely; for the strongly affiliated (just over a third of the American population), the trend between 1990 and the present is a flat line, their numbers neither growing nor collapsing but holding steady across an era of supposedly dramatic religious change.

Three reasons the narrative of rapid secularization is incomplete.
— Read on www.nytimes.com/2019/10/29/opinion/american-christianity.html