CCC 444
© Libreria Editrice Vaticana Source: vatican.va
The Gospels report that at two solemn moments, the Baptism and the Transfiguration of Christ, the voice of the Father designates Jesus his "beloved Son". Cf. Mt 3:17; cf. 17:5. Jesus calls himself the "only Son of God", and by this title affirms his eternal pre-existence. Jn 3:16; cf. 10:36. He asks for faith in "the name of the only Son of God". Jn 3:18. In the centurion's exclamation before the crucified Christ, "Truly this man was the Son of God", Mk 15:39. that Christian confession is already heard. Only in the Paschal mystery can the believer give the title "Son of God" its full meaning.
Read the full chapter 2. I Believe in Jesus Christ, the Only Son of God ¶422–682