For a Christian, believing in God cannot be separated from believing in the One he sent, his "beloved Son," in whom the Father is "well pleased"; God tells us to listen to him.(Mk 1:11; cf. Mk 9:7)
The Lord himself said to his disciples: "Believe in God, believe also in me."(Jn 14:1)
We can believe in Jesus Christ because he is himself God, the Word made flesh: "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)
Because he "has seen the Father," Jesus Christ is the only one who knows him and can reveal him.(Jn 6:46; cf. Mt 11:27)
Jesus revealed that God is Father in an unheard-of sense: he is Father not only in being Creator; he is eternally Father by his relationship to his only Son who, reciprocally, is Son only in relation to his Father: "No one knows the Son except the Father, and no one knows the Father except the Son and any one to whom the Son chooses to reveal him."(Mt 11-27)
Peter could recognize the transcendent character of the Messiah's divine sonship because Jesus had clearly allowed it to be so understood. To his accusers' question before the Sanhedrin, "Are you the Son of God, then?" Jesus answered, "You say that I am."(Lk 22:70; cf. Mt 26:64; Mk 14:61-62)
Well before this, Jesus referred to himself as "the Son" who knows the Father, as distinct from the "servants" God had earlier sent to his people; he is superior even to the angels.(cf. Mt 11:27; Mt 21:34-38; Mt 24:36)
He distinguished his sonship from that of his disciples by never saying "our Father", except to command them: "You, then, pray like this: 'Our Father'", and he emphasized this distinction, saying "my Father and your Father".(Mt 5:48; Mt 6:8-9; Mt 7:21; Lk 11:13; Jn 20:17)
But at the same time, this truly human knowledge of God's Son expressed the divine life of his person.(cf. St. Gregory the Great, "Sicut aqua" ad Eulogium, Epist. Lib. 10, 39 PL 77, 1097 Aff.; DS 475)
"The human nature of God's Son, not by itself but by its union with the Word, knew and showed forth in itself everything that pertains to God."(St. Maximus the Confessor, Qu. et dub. 66 PG 90, 840A)
Such is first of all the case with the intimate and immediate knowledge that the Son of God made man has of his Father.(cf. Mk 14:36; Mt 11:27; Jn 1:18; Jn 8:55; etc)
The Son in his human knowledge also showed the divine penetration he had into the secret thoughts of human hearts.(cf. Mk 2:8; Jn 2 25; Jn 6:61; etc)
2603 Please be patient! This CCC paragraph has not been loaded yet. You may find the reference at the Vatican website.
2779 Before we make our own this first exclamation of the Lord's Prayer, we must humbly cleanse our hearts of certain false images drawn "from this world." Humility makes us recognize that "no one knows the Son except the Father, and no one knows the Father except the Son and anyone to whom the Son chooses to reveal him," that is, "to little children." The purification of our hearts has to do with paternal or maternal images, stemming from our personal and cultural history, and influencing our relationship with God. God our Father transcends the categories of the created world. To impose our own ideas in this area "upon him" would be to fabricate idols to adore or pull down. To pray to the Father is to enter into his mystery as he is and as the Son has revealed him to us.
The expression God the Father had never been revealed to anyone. When Moses himself asked God who he was, he heard another name. The Father's name has been revealed to us in the Son, for the name "Son" implies the new name "Father."