The Gospel reading for Christmas Day is John 1:1-14, sometimes extending to John 1:18, which adds John the Baptist’s prophecy (verse 15). The prophet (not the Gospel writer and Apostle) is also referred to in verses 6 through 8:

The Word Became Flesh

 1 In the beginning was the Word, and the Word was with God, and the Word was God. 2He was in the beginning with God. 3 All things were made through him, and without him was not any thing made that was made. 4 In him was life, and the life was the light of men. 5 The light shines in the darkness, and the darkness has not overcome it.

 6There was a man sent from God, whose name was John. 7He came as a witness, to bear witness about the light, that all might believe through him. 8 He was not the light, but came to bear witness about the light.

 9 The true light, which enlightens everyone, was coming into the world. 10He was in the world, and the world was made through him, yet the world did not know him. 11He came to his own, and his own people did not receive him. 12But to all who did receive him, who believed in his name, he gave the right to become children of God, 13who were born, not of blood nor of the will of the flesh nor of the will of man, but of God.

 14And the Word became flesh and dwelt among us, and we have seen his glory, glory as of the only Son from the Father, full of grace and truth.

Today’s Bible commentary — excerpted (there is much more at the link) — is from Matthew Poole’s English Annotations on the Holy Bible. Emphases mine below:

Was the Word, that is, the eternal Son of God, the Lord Jesus Christ … Nor is Christ in this text alone called the Word, but 1 John 1:1, the Word of life; so Revelation 19:13: and there are some who think he is so called, Luke 1:2, comparing that text with 2 Peter 1:16, as also Psalms 33:6Besides, it is observed, that this term was more acceptable both to the Jews and the heathens, than the term of Christ, or the Son of God, would have been; for there was nothing more abhorred by the Jews than the latter … The evangelist therefore calleth Christ, to whom he was about to attribute the creation, the Word; not the word of God (so the Scriptures are called); to distinguish Christ in this notion from the revelation of the Divine will to the prophets, he is only called the Word, though he was the Son of God. Nor is it said, that in the beginning was the Word created, (as is said of the heavens and the earth, Genesis 1:1), but was the Word: this proveth the eternal existence of the Second Person in the Trinity; for what was in the beginning did not then begin to be: the term the Word, without the addition of God, speaketh him a subsistence; and it being said, that in the beginning he was, speaks his eternal existence; for what had a being in the beginning of time must needs be eternal, nothing being when time began but what was eternal. To this purpose are those texts, Psalms 90:2Proverbs 8:22-31John 17:5Ephesians 1:42 Thessalonians 2:13, which two texts compared show, In the beginning, here used, to be the same with before the foundation of the world: so 2 Timothy 1:9.

And the Word was God: lest any should say, What but God can be eternal, or be said to have been and had an existence in the beginning of the world? The evangelist addeth, that the Word was God: that is, the person or subsistence spoken of and intended by him was the Divine Being, which is but one; though in it there be three distinct subsistences, all make but one and the same Divine Being. The first thing spoken here of Christ attributes to him eternity; the second speaks his relation to the Father; this speaks the oneness and sameness of his essence with that of the Father. The term God, which in the foregoing words is to be taken personally for God the Father, is here to be taken essentially, as it signifieth the Divine Being.

Verse 2 – These words of the evangelist are a further confirmation and explication of what the evangelist had said before; asserting the eternity of the Son, and his relation to the Father, and oneness of essence with the Father. Whether the evangelist, forewarned by the Spirit of God, did add this repetition to forearm Christians against those errors which did afterward trouble the church, I cannot say; but certain it is, that these words do effectually confute the Eunomians, who distinguished between the Word which in the beginning was with God, and that Word by which all things were made; and the Arians, who make the Father to have existed before the Son; as also the Anomians, who would make the Father and the Son diverse both in nature and will. Some others make this verse a transition to John 1:4, and the sense to be, This same was not manifest to the world from the beginning of the world, but was with God until he came to be manifested in the flesh: thus, 1 John 1:2, it is said, he was with the Father, and was manifested unto us. He was manifested in the flesh, 1 Timothy 3:16.

Verse 5 – The light shineth in darkness: he had said before, that life was in Christ, in him as in the fountain; and the life in him was the light of men, giving light to men. Now this light which was in him had its emanations (as light in the sun); and the darkness, that is, men of dark minds, (the abstract being put for the concrete) …

Verse 9 – Which lighteth every man that cometh into the world; he lighteth not the Jews only, (as the prophets of old), but both the Jews and Gentiles. Some understand this of the light of reason; but besides that reason is no where in holy writ called light, neither did this illumination agree to Christ as Mediator. It is rather therefore to be understood of the light of gospel revelation, which Christ caused to be made to all the world, Matthew 28:19Mark 16:15The words in the Greek are so, as they may either be translated as we read them, or thus, who coming into the world, enlightened every man: a more universal spiritual light, or means to come to the knowledge of God, overspreading the world after Christ’s coming, than before. So John 7:46, I am come a light into the world. And it is by some observed, that the phrase cometh into the world, doth not barely signify a being born, but being sent into the world by the Father, being sanctified, as in John 10:36 17:18.

Verse 10 – He was in the world; he was in the place called the world, and amongst the men of the world; for so the term world is often taken, John 16:282 Peter 3:6. Christ, before he came in the flesh, was in it; filling both the heavens and the earth, and sustaining it by the word of his power, and manifesting his will to it, more immediately to Moses and to the prophets, and more mediately by Moses and by the prophets.

And the world knew him not; and the men of the world took no notice of him, did not acknowledge him, believe in him, nor were subject to him; so the word knew often signifies, (according to the Hebrew idiom), John 10:14,15,27; not a bare comprehension of an object in the understanding, but suitable affections: so Matthew 7:231 John 3:1. This is not to be understood of all individual persons in the world; for Abraham, Isaac, and Jacob, and David, and many particular persons, did in this sense know him; but the generality of the world did not. The heathens did not, (who are sometimes called the world, distinctively from the Jews, 1 John 2:21 Corinthians 1:21), and most of the Jews did not, though some did.

Verse 11 – And his own received him not; whom in this way of coming they did not receive, believing neither the testimony given by his prophets, nor by the Baptist, nor by himself, John 5:43.

Verse 12 – But as many as received him; though the generality of those amongst whom Christ came received him not in the manner before expressed, yet some did own him, believed in him and submitted to him; and to as many as thus received him, not into their houses only, but into their hearts,

to them gave he power to become the sons of God; he gave a power, or a right, or privilege, not that they might if they would be, but to be actually, to become, or be, the sons of God by adoption; for believers are already the sons of God, Galatians 3:26, though it doth not yet appear what they shall be in the adoption, mentioned Romans 8:23, which the apostle calls the redemption of our body, viz. in the resurrection; hence the children of God are called the children of the resurrection, Luke 20:36.

To them that believe on his name; this is the privilege of all that believe in the name of Christ; by which term he opens the former term of receiving: to receive Christ, and to believe in his name, are the same thing. To believe in his name, is either to believe in him, Acts 3:16 or in the revelation of himself in the promises of the gospel. The proposition of God’s word is the object of faith of assent: but the person of the Mediator is the object of that faith which receiveth Christ; and those alone have a right to be the sons of God, and to the privileges peculiar to sons, who believe in Christ as revealed in the promises of the word of God, and there exhibited to men.

Verse 14 – the Son of God, called the Word, for the reasons before specified, was made truly man, as flesh often signifieth in holy writ, Genesis 6:12Psalms 65:2Isaiah 40:5,6; not a vile, despicable, mortal man

And we beheld his glory; and we beheld the signs and effects of his glory; many of which were seen, both at the time of his transfiguration, and at his passion, resurrection, and ascension; the glory of his grace, holiness, truth, miraculous operations, &c.

The glory as of the only begotten of the Father; which glory was the glory of the only begotten of the Father; for the particle as here doth not signify likeness, but truth, Nehemiah 7:2Job 24:14.

Full of grace and truth, as he was God manifested in the flesh. Grace signifieth love and good will, out of which it was that he delivered us from the curse and rigour of the law (to which grace is opposed). He was also full of truth, both as truth is opposed to falsehood, and to the shadows and figures of the law; and Christ was full of truth as he was the antitype to all the ceremonies, and all the promises had and have their completion and reality in him: see John 14:17Romans 15:82 Corinthians 1:20. Truth also may signify the sincerity and integrity of Christ’s life, as he was without guile.