CIC 151 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.1 The Lord himself said to his disciples: “Believe in God, believe also in me.”2 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.”3 Because he “has seen the Father”, Jesus Christ is the only one who knows him and can reveal him.4

CIC 422 ‘But when the time had fully come, God sent forth his Son, born of a woman, born under the law, to redeem those who were under the law, so that we might receive adoption as sons.’5 This is ‘the gospel of Jesus Christ, the Son of God’:’6 God has visited his people. He has fulfilled the promise he made to Abraham and his descendants. He acted far beyond all expectation – he has sent his own ‘beloved Son’.7

1 Mk 1:11; cf. 9:7.
2 Jn 14:1.
3 Jn 1:18.
4 Jn 6:46; cf. Mt 11:27.
5 Gal 4:4-5.
6 Mk 1:1.
7 Mk 1:11; cf. Lk 1:5, 68.