At St. Paul's we have three Christ Masses, partly out of accommodation to the long held Christmas habits of people (hence the 7 pm Christmas Eve), partly out of an awareness that the best of all times to celebrate Christ Mass is at midnight, as the Introit has it, "When all was still and it was midnight, thine Almighty Word, O Lord, descended from the royal throne," and partly because Christmas morning is hardly Christmas morning without Mass (hence the third Christ Mass at 10 am on the 25th).
It's nice for me, actually, to get to approach the incarnation in three separate ways each year, and not think I have to get it all into one sermon. So at the first, I preached the meaning of the angel's message, "Fear not" (here's the audio for the Gospel and sermon). For the second--which always seems to me the most sublime, maybe because it's in the midst of night when all is still--I preached the idea of most important place being Bethlehem and the manger rather than Jerusalem or some other great place, the most significant people being shepherds rather than dignitaries or kings, and how also here and now, the most important place is the Christ Mass, this small and humble place the world likewise does not seem to notice (here's the audio for the Gospel and sermon at Midnight Mass). This morning's Third Christ Mass, whose Gospel is the one in St. John 1 (the Word became flesh), I preached essentially on the fact that "God is great" is not a confession of true faith, whether said by Muslims or by people who like to sing "How Great Thou Art." The real faith is a scandal to people who like to emphasize those things which ought to go without saying (of course God is great; that's not saying anything). It is the fact that God has sullied Himself with the filth of the human race and bound Himself to us for all eternity: "The Word became flesh." That audio is here.