While Shepherds Watched is a great hymn.
...except for the last verse, which records what the angels sang as recorded in Luke 2:14. The carol is based on the AV, which (at this point) used limited manuscript evidence to opt for its translation. The result is that most people learn what the angels sang from the carol, not from Luke’s gospel, and think that Christmas is about spreading good will around. (I know I know, it is in part – but not according to the angels, and slightly more indirectly).
For those interested, the textual issue is whether “good-will” is a nominative or a genitive. The nominative means there are 3 results of the birth of Jesus. 1. Glory to God. 2. Peace to earth. 3. Good will to men. The genitive means there are just 2: 1. Glory to God. 2. Peace to men of good-will. “Men of good-will” is a technical term for the elect in 1st century Judaism (apparently, according to Darrell Bock). Both manuscript evidence and the text “which best explains the existence of the other texts” rule point firmly to a genitive. If that is the case, the key is to link into the magnificat, and say that peace comes to those who fear God.
So, I’ve written an alternative last verse
All glory be to God who lives
In Heaven’s highest place;
And on the earth be peace for all
To whom God gives his grace.