Christmas carols are at the heart of all that tradition. For my seasonal music taste, the more medieval the better. Give me "Coventry Carol," "Verbum caro factum est" and "Gaudete." But most of our Christmas notions are Victorian innovations, with a Dickens Christmas as the apotheosis of the holiday.
Because singing carols is part of the ritual, it is satisfying even when we don't quite understand what it's all about. One carol frequently heard this time of year is an example—"God Rest Ye Merry, Gentlemen."
Notice where the comma goes in that title. This is where even Dickens—or, at least a walk-on character in "A Christmas Carol"—misunderstands this carol. From "Stave I, Marley's Ghost":
"Foggier yet, and colder! Piercing, searching, biting cold. If the good Saint Dunstan had but nipped the Evil Spirit's nose with a touch of such weather as that, instead of using his familiar weapons, then indeed he would have roared to lusty purpose. The owner of one scant young nose, gnawed and mumbled by the hungry cold as bones are gnawed by dogs, stooped down at Scrooge's keyhole to regale him with a Christmas carol: but at the first sound of —
"God bless you, merry gentleman!
May nothing you dismay!"
Scrooge seized the ruler with such energy of action, that the singer fled in terror, leaving the keyhole to the fog and even more congenial frost."
Not only does the hapless singer change "rest" to "bless," he, or the author, moves the comma so that he is calling for a blessing on one merry gentleman, not an apt description of old Ebenezer Scrooge.
The more accepted version has us wishing joy and pleasantry to uncharacterized gentlemen. The "rest" here means "keep" or "make." You may also note that Dickens's caroler says "you" rather than "ye." People who look into this sort of thing say the carol first appears in the 18th century with "you" in the first line. Later, "ye" is substituted, perhaps to make the carol more…medieval.
Apparently 18th century carolers agreed with me. Medieval is better.
N.B. The reference to St. Dunstan in the Dickens quote alludes to a legend that came into currency in the 11th century about the 10th century Archbishop of Canterbury. Before his elevation, the Benedictine monk worked as a blacksmith or silversmith. The legend says the Devil appeared to him in his cell and tempted him, but Dunstan got the better of him by clamping his metal-working tongs on Old Hob’s face. That's going medieval on him, for sure.