Messiahmas and David
The links between David and Christmas are clear enough on the surface of the various texts. It is after all an event that happens in Bethlehem, the city of David, and Joseph and Mary are there precisely because Joseph is of David’s lineage (Lk 2.4).
But as well as what is quite explicit, there are also other undertones and overtones from the David story.
For overtones, we can simply note that just as God passed over the “obvious” choices among Jesse’s sons in favour of the shepherd boy, so too God passes over the “obvious” choices regarding whom will receive the proclamation of the birth of the Messiah, and sends His army to make the royal announcement to… a bunch of shepherds.
Undertones: In Matthew 2, we find Herod making the mothers of Bethlehem childless; in the few verses immediately preceding the record of David’s anointing, we find Samuel hacking Agag of Amalek to pieces with the words, “As your sword has made women childless, so shall your mother be childless among women” (1 Sam 15.33). The connection gives us a pretty good idea what is going to happen to Herod very shortly, and so we are not surprised to learn of his death not far down the road.