After some light(ish) Christmas reading? Try Athanasius’ On the Incarnation. It’s short (150 or so pages on my phone) and because it’s translated from Latin, relatively easy to read1. It’s a beautiful book too, one of the first defences of Christ’s full divinity and full humanity that we have recorded (outside of the Bible).
What, then, was God to do? What else could He possibly do, being God, but renew His Image in mankind, so that through it men might once more come to know Him? And how could this be done save by the coming of the very Image Himself, our Saviour Jesus Christ? Men could not have done it, for they are only made after the Image; nor could angels have done it, for they are not the images of God. The Word of God came in His own Person, because it was He alone, the Image of the Father Who could recreate man made after the Image. In order to effect this re-creation, however, He had first to do away with death and corruption. Therefore He assumed a human body, in order that in it death might once for all be destroyed, and that men might be renewed according to the Image. The Image of the Father only was sufficient for this need. Here is an illustration to prove it.
You know what happens when a portrait that has been painted on a panel becomes obliterated through external stains. The artist does not throw away the panel, but the subject of the portrait has to come and sit for it again, and then the likeness is re-drawn on the same material. Even so was it with the All-holy Son of God. He, the Image of the Father, came and dwelt in our midst, in order that He might renew mankind made after Himself, and seek out His lost sheep, even as He says in the Gospel: “I came to seek and to save that which was lost. This also explains His saying to the Jews: “Except a man be born anew .. .” a He was not referring to a man’s natural birth from his mother, as they thought, but to the re-birth and re-creation of the soul in the Image of God.
1 Some of the Puritans who wrote English (Cough John Owen Cough) are hard to read because their English is five hundred years old, whereas even the free, passed-copyright, translations from Latin or Greek are generally only two hundred years old and so in much moderner idiom. Just thank the Lord you don’t speak German. I have German friends who’d rather read Luther in translated English than the original German, because the German from that period is so hard to understand now.