In my public elementary school in the early 70s, we sang all of the Christmas songs including the religious ones. We ALSO sang a couple of explicitly Hanukkah songs. The Jewish kids sang ours and we sang theirs, and if anybody opted out, no big deal. (some of us mouthed EVERYTHING to get out of singing). Even outside of Christmas, we sung religious songs of obvious historical significance. As a Catholic, I found the words of Chester particularly parochial . “New England’s God forever reigns” sounds more like a collegiate fight song than a true hymn. As long as there is no chance of confusion, or saying anything that my faith would find blasphemous, no prob. No one thought I was Jewish because I sang “Tis the week of Hanukkah”.
So far in Utah, they still sing/play Christmas songs, even religious ones! My 11 year old granddaughter’s been learning to play the Viola this year, she was in the Christmas concert and the group from her school did play at least one religious-themed song: “God Rest Ye Merry Gentlemen”, and a couple others. The other students from a another school who were more advanced, played other songs, such as: “Silent Night”, “We Three Kings From Orient Are” and “Alleluia Chorus”! We in Utah have been generally more fortunate in that we were founded by a religious group, (we have others besides LDS, of course) so we haven’t had the problems other states have had, yet! (I do say, “yet”)However, that could change in future!(heaven forbid) Massachusetts was also founded that way, as was Maryland, and look what happened to them! (grimace..)