When I was in high school choir, one of our favorite warm-up songs was "The Lord Bless You and Keep You". You probably couldn't get away with that today. We also used 1930's era hymnals for sight-reading. Zgirl can attest that on more than one occasion, singing "The Lord Bless You and Keep You" was a religious experience in itself. I remember very specifically feeling the very presence of G-d in the room when we were really tight.
O Holy Night gives me that same feeling.
We went to a "Holiday Concert" at my grandsons' school last year. There was one Christmas song in the whole concert. Secular, of course.
"singing "The Lord Bless You and Keep You" was a religious experience in itself."
Among the most beautiful pieces ever composed. Many choirs and chorales sing it after every rehearsal and after concerts.
One those pieces that if sung badly is good, if sung well will make good men cry and bad men sweat.