The Trinity Fully Revealed
And Jesus, when he was baptized, went up straightway out of the water: and, lo, the heavens were opened unto him, and he saw the Spirit of God descending like a dove, and lighting upon him: And lo a voice from heaven, saying, This is my beloved Son, in whom I am well pleased. Mat 3:16.17
Remark here also another thing altogether notable. It is in and by the voluntary humiliation of Jesus that all the Trinity is for the first time fully revealed. The Son is there, the object specially conspicuous as man; the Holy Spirit comes and abides on Him; and the voice of the Father owns Him: marvelous revelation associated with the position that the Son had taken!
The Son is recognized as Jehovah in Psa. 2 The Holy Spirit is found everywhere in the Old Testament. But the full revelation of the three persons in the unity of God—the basis of Christianity—is reserved for the moment when the Son of God takes His place in the midst of the poor of His flock, His true place in the race in which He had His delights, the sons of men. What grace is that of Christianity! what a place is that where our hearts are found, if taught of God we have learned to know this grace and Him in whom it is come to us! Here then is our position according to this grace in Christ Jesus, before God our Father accepted in the Beloved.
JND - On the Gospel of Matthew, ch. 3.