Jesus Christ, God the Son, reveals to us the mystery of the inner life of God, showing through his words and deeds that God is not a solitary being, but is a communion of Persons, Father, Son and Holy Spirit. Jesus is the Son that has come to humanity to fully reveal the countenance of the Father, showing us the Eternal Father’s face through the incarnation.

In revealing to us the face of the Father, Jesus breaks open eternity for mankind, making a relationship with the Father through the Son in the Holy Spirit a real possibility for each and every one of us. The Trinity is as much the main message of the Good News as is the cross and Resurrection.

This self-giving, life-giving love is the heart of the Blessed Trinity and therefore, it is the heart of our Christian faith and morality.

The Old Testament utilizes the understanding of God as “father” only as a simile or metaphor, or in the vague sense of the deity as father over creation. In the whole Old Testament even this pared down usage of God as or like a Father is found about sixteen times.

While once the Scriptures get to the Gospel of Matthew, the first book in the New Testament, the Fatherhood of God is a dominant theme and is central not only to Jesus’ self-understanding, but is the key interpretive principle for the Sermon on the Mount in Matthew chapters 5-7, the longest single sermon of Christ.

Over and over we encounter the Son telling his disciples how to live as sons of the Father “who sees in secret”, the Father “who will reward you.” If you strip Jesus of his divine sonship, you strip him of his identity and his main pedagogy: sonship.

The Gospel is the proclamation that your sins are forgiven by the mercies of Christ and his cross and Resurrection, but that is only half the story. It is the proclamation that, because your sin is gone, Jesus restored your relationship with the Father and you are now able to be fully united to Him. The Gospel is the divine family reunion. Jesus does not save us without restoring us, that is, his redeeming love is meant to bring us home, not just to quarantine us from our sins.

Grace makes us one with God the Father in the Son, Jesus Christ, through his outpouring of the Holy Spirit on each and every one of His children. This is divine filiation, sonship. This is the mission of Christ and how he communicates the inner life of the Trinity to humanity, revealing not only God’s self-giving love, but also His plan for humanity to be sons and daughters in the Son.

As Saint Athanasius said, “God became man so that men might become God.” We see this central notion of divine filiation in the beginning of his ministry in the Sermon on the Mount where every moral and religious teaching is based upon the Fatherhood of God (“...your Father who sees in secret will reward you”). This divine sonship of the faithful runs through the whole of the Gospel like a golden thread.

In John 14 Jesus says to his Apostles gathered in the Upper Room: “I am the way, the truth and the life. No one comes to the Father except through me. If you know me, then you will also know my Father. From now on you do know Him and have seen Him”.

These are some of the most powerful words in all of Scripture. Jesus clearly and emphatically lays out the union between his mission (works) and his identity, between his identity and that of the Father.

Here enters Philip, as non-comprehending as the rest, but still eager, says to him, “Master, show us the Father. That will be enough for us.” And Jesus, probably with his head in his hands, replies, “Have I been with you for so long a time and you still do not know me, Philip? Whoever has seen me has seen the Father. How can you say, ‘Show us the Father?’ Do you not believe that I am in the Father and the Father is in me?”

If you know Jesus, you know the Father who sent him. If you have seen his works, then you are seeing the work of the Father. Jesus is always revealing to those who have the eyes so as to see the countenance and beauty of the Father.

In so revealing the inner life of God to humanity, the Son pours out the Spirit of the Father upon all who are called to be his disciples, united them to the Trinity through God’s dwelling in the hearts of everyone who has faith. “Remain in me and I will remain in you” (John 15:4).

This is key: his identity as the only-begotten Son of the Father becomes the disciple’s identity through grace, provided one remains in him. Saint Athanasius said, “What He is by nature, we too shall be by grace.”