Here are some poetic words from Saint Augustine’s Sermon 69: On the same words, John 1: “In the beginning was the Word, etc.” excerpted from the Nicene and Post-Nicene Fathers edited by Philip Schaff. There are some beautiful lines here on the Incarnation—the Word of God becoming flesh—that could make this a Christmas sermon.
Do not follow the current of the flesh. For this flesh is indeed a current; for it has none abiding. As it were from a kind of secret fount of nature men are born, they live, they die; or whence they come, or whither they go, we know not….