The Good News of salvation is that God our Father has revealed himself to the created universe in the person of his only son, the Lord Jesus Christ. The mysterious and transcendent God of past ages, the one who dwells in unapproachable light, made himself known to mankind's first parents in the garden. Then, through the covenant with Noah, the election of Abraham, the formation of his people Israel, the Mosaic law, and the prophets He became more and more immanent. Jesus Christ is the eternal Word through which this revelation has been transmitted to us by the heavenly Father in the power of the Holy Spirit. Divine revelation, quite simply, is God revealing himself to us in the person of his son, Jesus Christ.
Analogies are useful, even though they are imperfect.
God is one. He is also three. The one God, who is Father, Son, and Holy Spirit has revealed himself to us. The Lord Jesus, while on this earth, taught orally. The ones that he taught first were the 12 men that he called to be his closest collaborators in his mission of salvation, the apostles.