These words were spoken to prove that Jesus Christ is the Son of God and the Apostle. Formerly He was the Word, appearing sometimes in the form of fire and sometimes in the likeness of bodiless beings.
Now, by the will of God, He became man for the human race. He also endured the sufferings to which He was subjected, through the activity of demons, by the senseless Jews.
Yet the Jews, although it is plainly written in the writings of Moses, "And the Angel of God spoke to Moses in the fire burning in the thorn bush and said: I AM, the God of Abraham, the God of Isaac, and the God of Jacob," assert that the Father of all and Creator spoke in this way.
Therefore the prophetic Spirit, rebuking them, said: "Israel does not know Me; My people have not understood Me" (Is 1:3).
Likewise Jesus, as I noted above, said while among them: "No one knows the Father except the Son; nor the Son except the Father, and those to whom the Son reveals Him."
Thus the Jews always thought that the Father of all spoke with Moses. Yet the One who spoke with him is the Son of God, who was called both Angel and Apostle.
Therefore they are rightly rebuked by the prophetic Spirit and by Christ Himself, because they know neither the Father nor the Son.
Those who call the Son the Father plainly show that they do not know the Father. Nor do they know that the Father of all has a Son, who, being the firstborn Word of God, is also God.
He formerly appeared to Moses and the other prophets in the form of fire and in a bodiless likeness. Now, in the times of your dominion, as I said above, He became man from the Virgin.
This was by the will of the Father, for the salvation of those who believe in Him. He endured humiliation and suffering, that by His death and Resurrection He might conquer death.
What was said to Moses from the bush, "I AM, the God of Abraham, and the God of Isaac, and the God of Jacob, and the God of your fathers," means that they remain even after death and are men of the same Christ.
For they were the first of all men to devote themselves to seeking God. Abraham was the father of Isaac, and Isaac of Jacob, as Moses also wrote.