Jesus enjoys a very special relationship with "his" Father through his words and actions. John's Gospel stresses that what he communicates to men is the fruit of this intimate and extraordinary union: "The Father and I are one" (Jn 10:30). And again: "All that the Father has is mine" (Jn 16:15). There is a reciprocity between the Father and the Son in what they know of each other (cf. Jn 10:15), in what they are (cf. Jn 14:10), in what they do (cf. Jn 5:19; 10:38) and in what they possess: "Everything of mine is yours, and everything of yours is mine" (Jn 17:10). It is a reciprocal exchange which finds full expression in the glory Jesus receives from the Father in the supreme mystery of his Death and Resurrection, after he himself had given it to the Father during his earthly life: "Father, the hour has come; glorify your Son that the Son may glorify you.... I glorified you on earth ... and now Father, glorify me in your own presence ..." (Jn 1:1, 4f.).
This essential union with the Father not only accompanies Jesus' activity, but defines his whole being. "The Incarnation of God's Son reveals that God is the eternal Father and that the Son is consubstantial with the Father, which means that, in the Father and with the Father, the Son is one and the same God" (CCC, n. 262). The Evangelist John stresses that it is precisely to this divine claim that the religious leaders of the people react, for they cannot tolerate him calling God his Father and therefore making himself equal to God (Jn 5:18; cf. 10:33; 19:7).
In virtue of this consonance in being and acting, Jesus reveals the Father in words and deeds: "No one has ever seen God: the only Son, who is in the bosom of the Father, he has made him known" (Jn 1:18). As we are told in the account of the Synoptic Gospels (cf. Mk 1:11; Mt 3:17; Lk 3:22), the fact that Christ is the "beloved" one is proclaimed at his Baptism. The Evangelist John refers this back to its Trinitarian root, that is, to the mysterious existence of the Word "with" the Father (Jn 1:1), who generates him from all eternity.
The Apostle John offers us a key to this mystery which infinitely surpasses our understanding, when in his First Letter he proclaims: "God is love" (1 Jn 4:8). This summit of revelation indicates that God is agape, that is, the gratuitous and total gift of self which Christ proved to us, especially by his death on the Cross. The Father's infinite love for the world is revealed in Christ's sacrifice (cf. Jn 3:16; Rom 5:8). The capacity to love infinitely, to give oneself without reserve or measure, belongs to God. By virtue of his being Love, even before his free creation of the world he is Father in the divine life itself: a loving Father who generates the beloved Son and gives rise with him to the Holy Spirit, the Person-Love, the reciprocal bond of communion.
A great mystery, a mystery of love, an ineffable mystery, before which words must give way to the silence of wonder and worship. A divine mystery that challenges and involves us, because a share in the Trinitarian life was given to us through grace, through the redemptive Incarnation of the Word and the gift of the Holy Spirit: "Anyone who loves me will be true to my word, and my Father will love him; we will come to him and make our dwelling-place with him" (Jn 14:23).
For us believers, the reciprocity between the Father and the Son thus becomes a principle of new life which enables us to participate in the very fullness of the divine life: "Whoever confesses that Jesus is the Son of God, God abides in him, and he in God" (1 Jn 4:15). The dynamism of Trinitarian life is lived by creatures in such a way that everything is directed to the Father, through Jesus Christ, in the Holy Spirit. This is what the Catechism of the Catholic Church stresses: "The whole Christian life is a communion with each of the Divine Persons, without in any way separating them. Everyone who glorifies the Father does so through the Son in the Holy Spirit" (n. 259).
The Son has become "the first-born among many brethren" (Rom 8:29); through his death the Father communicated new life to us (1 Pt 1:3; cf. also Rom 8:32; Eph 1:3), so that we might call upon him in the Holy Spirit with the same term that Jesus used: Abba (Rom 8:15 Gal 4:6). St Paul explains this mystery further, saying that "The Father ... has qualified us to share in the inheritance of the saints in light. He has delivered us from the dominion of darkness and transferred us to the kingdom of his beloved Son" (Col 1:12-13). And this is how Revelation describes the eschatological destiny of whoever fights and conquers the power of evil with Christ: "He who conquers, I will grant him to sit with me on my throne, as I myself conquered and sat down with my Father on his throne" (Rv 3:21). Christ's promise opens to us the wondrous prospect of sharing in his heavenly intimacy with the Father.