The NY TImes has an extended article on one chord in "Oh Come, All Ye Faitful"

[url=https://www.nytimes.com/2022/12/21/arts/music/o-come-all-ye-faithful-christmas-chord.html?unlocked_article_code=L77JJA9srehbTQXcoytb1OX-4BpUkjbm_uB3pXEmOkRl-WOCJQ7zRm5fUiZIeQ7O1vgml3mGUQ8JkOE0HbKhtHW0yDN1MUMvKmKNASh3go-6w-0Gl4HjyxV9MsR3xiKlcWiUZ4P6v8Xgg-NDeHocV0lR-WEZ-G9kkKOcVLidTReSbROoo0jFJfubE1Fpa5CSZdPjXIksiFOKKSlb9tEXGrGzIMFUIe8RIdckkhdxhE11PNJg0e6tWVljZHDMZbAzhzxAIOBKa6xAs_RLDZ8m4D0gmEG9pAYhivHntWEHeMns8-Npw5vYFCEMkcTprH7PL1KpGdhtLjrsJpkClOJIQyBy1r_8CyxAentP8PqOFzZ_fqU&smid=share-url]‘Everyone Wants to Hear’ This One Chord in a Christmas Carol

“It’s a startling moment,” David Hill, the musical director of the Bach Choir, said in a telephone interview. “I remember being a boy of 10 playing it in my church in Carlisle, and loving every moment of it, thinking: ‘What is this? This is outrageous!’”

When I was growing up, our Lutheran Hymnal did not contain this arrangement but it does seem to be what our organist was playing. I knew nothing of half-diminished sevenths, of course.