1. In the previous catechesis we showed, on the basis of the synoptic Gospels, how faith in the divine sonship of Christ is being formed by revelation of the Father in the consciousness of his disciples and listeners, and first of all in the consciousness of the apostles. To create the conviction that Jesus is the Son of God in the strict and full (not metaphorical) sense of this word, contributes above all the testimony of the Father himself, who "reveals" in Christ his Son ("my Son") through the theophanies that took place at the baptism in the Jordan and then during the transfiguration on the mountain. We have also seen how the revelation of the truth about the divine sonship of Jesus reaches through the work of the Father the minds and hearts of the apostles, as appears in the words of Jesus to Peter: "Neither flesh nor blood has revealed it to you, but my Father who is in heaven" (Mt 16:17).

2. In the light of this faith in the divine sonship of Christ, a faith that gained much greater strength after the resurrection, one must read the entire Gospel of John, and particularly its Prologue (Jn 1:1-18). It is a singular synthesis expressing the faith of the apostolic Church: of that first generation of disciples, to whom it was given to have contact with Christ, either directly or through the apostles who spoke of what they had personally heard and seen and in whom they discovered the fulfilment of all that the Old Testament had foretold about him. What had already been revealed previously, but in a certain sense was covered with a veil, now, in the light of the facts of Jesus, and especially on the basis of the Easter events, gained transparency, became clear and comprehensible.

In this way, the Gospel of John (which among the four Gospels was written last) constitutes in a sense the most complete account of Christ as the Son of God - Son 'consubstantial' with the Father. The Holy Spirit, promised by Jesus to the apostles, who was to "teach them all things" (cf. Jn 14:26), truly enables the evangelist "to fathom the depths of God" (cf. 1 Cor 2:10) and express them in the inspired text of the Prologue.

In the beginning was the Word, and the Word was with God, and the Word was God. He was in the beginning with God: all things were made through him, and without him nothing was made of all that exists" (Jn 1:1-3). "And the Word became flesh and dwelt among us; and we beheld his glory, glory as of the only begotten of the Father, full of grace and truth" (Jn 1:14) . . . "He was in the world and the world was made through him, yet the world did not recognise him. He came among his people, but his own did not receive him" (Jn 1:10-11). "To those, however, who did receive him, he gave power to become children of God: to those who believe in his name, who were begotten not of blood, nor of the will of the flesh, nor of the will of man, but of God" (Jn 1:12-13). "God no one has ever seen: it is the only Son, who is in the bosom of the Father, who has revealed him" (Jn 1:18).

4. John's Prologue is certainly the key text, in which the truth about Christ's divine sonship finds its full expression. He who in time "became flesh", that is, man, is from eternity the Word Himself, that is, the only-begotten Son: the God "who is in the bosom of the Father". He is the Son "of the same substance as the Father", he is "God from God". From the Father he receives the fullness of glory. He is the Word "through whom all things were made". And therefore everything that exists owes to him that "beginning" of which the Book of Genesis (cf. Gen 1:1) speaks, the beginning of the work of creation. The same eternal Son, when he comes into the world as the "Word who became flesh" brings with him to humanity the fullness "of grace and truth". He brings the fullness of truth because he instructs about the true God whom "no one has ever seen". And he brings the fullness of grace because to all who receive him, he gives the strength to be born again of God: to become children of God. Unfortunately, the evangelist notes, "the world did not recognise him" and although "he came among his people", many "did not receive him".

5. The truth contained in the Johannine Prologue is the same truth we find in other books of the New Testament. Thus for example we read in the Epistle "to the Hebrews" that God "in these days has spoken to us through his Son, whom he made heir of all things and through whom he also made the world. This Son, who is the radiance of his glory and the stamp of his substance, and who upholds all things by the power of his word, after he has cleansed us from sins, is seated at the right hand of the majesty in the highest heaven" (Heb 1:2-3).

6. The Prologue of the Gospel of John (like the Epistle to the Hebrews), therefore expresses in the form of biblical allusions, the fulfilment in Christ of all that was said in the old covenant, beginning with the Book of Genesis through the law of Moses (cf. Jn 1:17) and the prophets to the books of wisdom. The expression "the Word" (who "in the beginning was with God") corresponds to the Hebrew word "dabar". Although the term 'logos' is found in Greek, the matrix is first and foremost Old Testament. From the Old Testament it simultaneously borrows two dimensions: that of "hochma" (wisdom), understood as God's "plan" regarding creation, and that of "dabar" (logos), understood as the realisation of that plan. The coincidence with the word 'logos', taken from Greek philosophy, facilitated the approach of these truths to minds formed by that philosophy.

7. Remaining now within the sphere of the Old Testament, precisely in Isaiah we read: the "word that came forth from my mouth shall not return to me without effect, without having done what I desire and without having accomplished that for which I sent it" (Is 55:11). Hence it appears that the biblical "dabar-word" is not only "word" but also "fulfilment" (deed). It can be said that already in the books of the old covenant there appears some personification of the "Word" (dabar, logos), as well as of "Wisdom" (sofia).

Indeed, we read in the Book of Wisdom:

(Wisdom) "is initiated into the knowledge of God and chooses his works" (Wis 8:4), and elsewhere: "With you is Wisdom, who knows your works, who was present when you created the world; she knows what is pleasing to your eyes and what is conformable . . . Send her from the holy heavens, from your glorious throne, that she may assist me and be with me in my labour, and that I may know what is pleasing to you" (Wis 9:9-10).

8. We are thus very close to the first words of John's Prologue. Even closer are those verses from the Book of Wisdom that say: "While a profound silence enveloped all things, and the night was in the middle of its course, your almighty word from heaven, from your royal throne . . . came into the midst of that land of extermination, bearing as a sharp sword your inexorable command" (Wis 18:14-15). However, this "word" alluded to in the wisdom books, that wisdom which from the beginning is with God, is considered in relation to the created world that it orders and directs (cf. Prov 8:22-27). "The Word" in John's Gospel, on the other hand, is not only "in the beginning", but is revealed as being all addressed to God (pros ton Theon) and being himself God! "The Word was God". He is the 'only-begotten Son, who is in the bosom of the Father'-that is, God-the-Son. He is in person the pure expression of God, the "radiation of his glory" (cf. Heb 1:3), "consubstantial with the Father".

9. It is precisely this Son - the Word who became flesh - to whom John bears witness at the Jordan. Of John the Baptist we read in the Prologue: "There came a man sent from God, and his name was John. He came as a witness to bear witness to the light . . ." (Jn 1:6-7). That light is precisely Christ - as the Word. We read again in the Prologue: "In him was life, and the life was the light of men" (Jn 1:4). This is "the true light, the light that enlightens every man" (Jn 1:9). The light that "shines in the darkness, but the darkness did not receive it" (Jn 1:5).

Therefore, according to the Prologue of John's Gospel, Jesus Christ is God, because He is the only-begotten Son of God the Father. The Word. He comes into the world as the source of life and holiness. Truly here we are at the central and decisive point of our profession of faith: 'The Word became flesh and came to dwell among us'.

[Pope John Paul II, General Audience 3 June 1987]