This Christmas carol is relatively easy to prepare.  It’s power comes as elements are added to each verse of the song. (You can listen to the entire song or the last 2 verses only.) 

1. A string quartet (or other instruments) plays the hymn out of the hymnbook.
2. The choir sings the 1^st verse accompanied by the string quartet, giving it a unique, lovely quality
3. The choir and the string quartet are joined by the organ for the 2^nd verse.  There is an obbligato added to the chorus sung by a few sopranos.
4. On the 3^rd verse, the congregation is invited to join the strings, organ and choir, along with the obbligato.

This could be used as a congregational number.  The choir parts all come from the hymnbook. The strings also play from the hymnbook except for the last verse chorus.  So the only new parts to learn are the obbligato and the 6 measures for strings which are repeated.  Sing!  Gloria in Excelsis!!