This Memo concerns not some breaking story but a potential scenario about U.S. "evangelical" Protestants that reporters on both the politics and religion beats should be watching.

For the umpteenth time we revisit the definition of this vibrant but challenged movement and its relation to a Republican Party that the secularized Donald Trump continues to dominate.

(See The Guy's effort at defining evangelicalism here, and remember that most media discussions involve White evangelicals only, since Black and Hispanic evangelicals are very different politically. And click here for a wave of tmatt posts on this topic.)

GetReligion team member Ryan Burge, an energetic political scientist who posts interesting data most days of the week, tweeted this chart on Sept. 16th showing how self-identified evangelicals described their own church attendance over a dozen years in Cooperative Election Study polling.

There's a clear developing trend. As recently as 2008, 58.6% of self-identified evangelicals said they worshiped weekly or more often, but less than half (49.9%) by 2020.

Over the same years, evangelicals who "seldom" or "never" attended grew from 16.1% to 26.7%. The slide did not begin with the Trump presidency but was already at work, since in 2016 the weekly-or-mores were down to 52.9% and seldom-or-nevers up to 22.6%.

The Guy considers attendance a good barometer of devotion, as a historically central value inside the evangelical subculture. We can speculate that similar downward slides might be occurring with other bonding activities in the evangelical tradition such as adult Bible classes, prayer meetings, small groups, daily devotions, evangelistic revivals and charity projects.

The numbers surely reflect the nation's 21st Century secularization. But Burge reaches the provocative conclusion that they mean evangelical "is not a religious term anymore." (What substitute word would suffice? There's a story theme for you.) Certain movement insiders have argued that a different label is needed because the term has taken on such a heavy Republican -- and Trumpublican -- flavor