Listening to Chopin's Nocturnes reminds me that there was one Kingdom Song (sorry I don't remember the title or number, and the French lyrics I have in mind wouldn't help), still sung in the 80's, which clearly borrowed the melody of Nocturne # 4 in F major.
There were many more "worldly tunes" in the former songbooks, but they had been either suppressed or modified to make the themes less recognisable (e.g. Beethoven's Appassionata theme in a song about Noah if I remember correctly).
Are those songs still sung?