This is another of the Advent songs from Gather 3rd ed. and is based on the “O” Antiphons. It is by Francis Patrick O’Brien. The guitar version plays it capo 3 but since it goes to an E in the verses I’d play it without a capo. It changes key for the verse after the last phrase of the chorus goes into odd territory tunewise. It still works.
GIA sell the sheet music and the text is in their preview.
My backing is in the original key.