Following yet more prompting I finally got around to expading my pitiful Van Morrison collection. Bought Astral Weeks and Inarticulate Speech of the Heart. Disturbed to see the latter dedicated to uberkook L.Ron Hubbard. Apparently he had some dabblings in that area, one hopes he has now come to his senses.
Anyway, I can report it wasn't just Christianity which forced people to make bad music in the '80s.