How long did it take him to write that book?
Did he identify this trend in 2014 and seek to prove it by 2016 and declare it correct in 2020?
Sounds like he had something to prove rather than something to observe.
“Did he identify this trend in 2014 and seek to prove it by 2016 and declare it correct in 2020?”
Shoot the messenger at your own peril. Understand that US society for good or bad was underpinned by Judeo-Christian values; Western European ethnicity; English common law and an accepted common language etc. It would be interesting to see a post-Christian America absent these underpinnings but fortunately I will likely not have that “opportunity.”
If you cannot see with your own eyes the things that the author describes in terms of demographic “diversity”, changes in local laws, new political faces and near empty church parking lots, you aren’t looking very hard.