It used to be much simpler.
When I was a kid growing up in Brooklyn I went to P.S.67.
We had "assemblies" where the entire school sat in the auditorium and sang Christmas Carols. "Silent Night", "Oh Come All Ye Faithful", "Little Town of Bethlehem", etc. We'd previously been taught the words by "the Music Teacher" in "Music Appreciation" class.
It did not prevent me from loving Chanukah or growing up as a proud Jew who would one day decide to live in Israel, his ancestral Jewish homeland.
Like I say, it used to be much simpler.