Here are some passages for reflection this Christmas day, from the Catechism and from an early Church Father, St. Athanasius.
Catechism of the Catholic Church, n. 460
“The Word became flesh to make us “partakers of the divine nature“[2 Pet 1:4]: “For this is why the Word became man, and the Son of God became the Son of man: so that man, by entering into communion with the Word and thus receiving divine sonship, might become a son of God.” [St. Irenaeus] “For the Son of God became man so that we might become God.” [St. Athanasius] “The only-begotten Son of God, wanting to make us sharers in his divinity, assumed our nature, so that he, made man, might make men gods.” [St. Thomas Aquinas]
St. Athanasius, selection from On the Incarnation of the Word (4th Century)
“But for the searching of the Scriptures and true knowledge of them, an honourable life is needed, and a pure soul, and that virtue which is according to Christ; so that the intellect guiding its path by it, may be able to attain what it desires, and to comprehend it, in so far as it is accessible to human nature to learn concerning the Word of God. For without a pure mind and a modeling of the life after the saints, a man could not possibly comprehend the words of the saints. For just as, if a man wished to see the light of the sun, he would at any rate wipe and brighten his eye, purifying himself in some sort like what he desires, so that the eye, thus becoming light, may see the light of the sun; or as, if a man would see a city or country, he at any rate comes to the place to see it—thus he that would comprehend the mind of those who speak of God must needs begin by washing and cleansing his soul, by his manner of living, and approach the saints themselves by imitating their works; so that, associated with them in the conduct of a common life, he may understand also what has been revealed to them by God, and thenceforth, as closely knit to them, may escape the peril of the sinners and their fire at the day of judgment, and receive what is laid up for the saints in the kingdom of heaven, which “Eye has not seen, nor ear heard, neither have entered into the heart of man,” (1 Cor 2:9) whatsoever things are prepared for them that live a virtuous life, and love the God and Father, in Christ Jesus our Lord: through Whom and with Whom be to the Father Himself, with the Son Himself, in the Holy Spirit, honour and might and glory for ever and ever. Amen.”
Source: New Advent