And this is life eternal, that they might know you the only true God, and Jesus Christ, whom you have sent.
All Commentaries on John 17:3 Go To John 17
Cyril of Alexandria
AD 444
CHAPTER V. That the Son will not be excluded from being true God, even though He named God the Father the only true God.
He defines faith as the mother of eternal life, and says that the power of the true knowledge of God will be such as to cause us to remain for ever in a state of incorruption, and blessedness, and sanctification. And we say that that is true knowledge of God, which cannot incur the reproach of turning aside to aught else, or running after things unseemly. For some have worshipped the creature rather than the Creator, and have dared to say to a block of wood: Thou art my Father; and to a stone, Thou hast begotten me. For to such abysmal ignorance did miserable men relapse, that they even gave, in all its fulness, the great Name of God, to senseless blocks of wood; and invested them with the ineffable glory of that Nature, which is over all. He calls God the Father, then, the only true God, by contrast to spurious gods, and with the intention to distinguish the true God, from those who are so named in error; for this is the object of His words. Very appropriately, then, He first speaks of God as being One and One only, and then makes mention of His own glory in the words: And Jesus Christ Whom Thou hast sent. For a man can in nowise attain to complete knowledge of the Father, unless side by side, and in most intimate connexion with it, he lay hold on the knowledge of His Offspring; that is, the Son. For, if a man know what the Father is, he cannot but know also the Son. When, then, He said that the Father was the true God, He did not exclude Himself. For being in Him, and of Him, by Nature, He will be also Himself the true God and the only God, as He is the only God: for beside Him, there is none other god who is the only true God. For the gods of the heathen are devils. For the creation is enslaved, and I know not how any worship them, or sink into such a slough of unreasoning and sensuous folly. With the many gods, then, in this world, who are erroneously so conceived, and have won this spurious title, the only true God is brought into contrast; and the Son also, Who is by Nature in Him, and of Him, at once in diversity and in identity of Nature, according to a natural Unity. I say in diversity of Nature, because He has in fact an individual Existence; for the Son is the Son, and not the Father. In identity of Nature also, because the Son, Who came forth from Him, is inseparably joined by Nature, with the existence of His Father. For the Father is one with the Son, even though He is the Father; and is so spoken of, because He did in fact beget Him.
This, then, He says, is eternal life, that they should know Thee the only true God, and Jesus Christ Whom Thou hast sent. Then one of those who are never weary of hearkening to the Scripture, and seriously pursue the study of Divine doctrines, will ask: Do we say that knowledge is eternal life; and that to know the one true and living God will suffice to give us complete security of expectation, and nothing else be lacking? Then how is faith apart from works dead? And when we speak of faith, we mean the true knowledge of God, and nothing else; for by faith comes knowledge: and the prophet Isaiah bears us witness, who said to some: If ye do not believe neither shall ye understand. And that the writings of the holy men are referring to the knowledge which consists in barren speculations, a thing wholly profitless, I think you will perceive from what follows. For one of the holy disciples said: Thou believest that God is one; thou doest well: the devils also believe and shudder. What then shall we say to this? How does Christ speak truth, when He says that eternal life is the knowledge of God the Father, the One true God, and (with Him) of the Son? I think, indeed, we must answer that the saying of the Saviour is wholly true. For this knowledge is life, travailing as it were in birth of the whole meaning of the mystery, and vouchsafing unto us participation in the mystery of the Eucharist, whereby we are joined unto the living and life-giving Word. And for this reason, I think, Paul says that the Gentiles are made fellow-members of the body and fellow-partakers of Christ; inasmuch as they partake in His blessed Body and Blood; and our members may in this sense be conceived of, as being members of Christ. This knowledge, then, which also brings to us the Eucharist by the Spirit, is life. For it dwells in our hearts, shaping anew those who receive it into sonship with Him, and moulding them into incorruption and piety towards God, through life according to the Gospel. Our Lord Jesus Christ, then, knowing that the knowledge of the One true God brings unto us, and, so to speak, promotes our union with, the blessings of which we have spoken, says that it is eternal life; insomuch as it is the mother and nurso of eternal life, being in its own power and nature pregnant with those things which cause life, and lead unto it.
And I think we ought attentively to observe in what way Christ says that the knowledge of the One true God is perfected in us in all its fulness. For see how it cannot exist apart from the contemplation of the Son, and it is clear that it cannot exist apart from the Holy Spirit; for such is the nature of the belief in each Person of the Trinity, according to the Scripture. The Jews indeed, following in the steps of Moses' commandments, rejected the many false gods, and betook themselves to the worship of the One true God, under his guidance. Thou shalt worship the Lord thy God, saith the Law, and Him only shalt thou serve. But those who still cling to the worship of the One true God, as not yet having complete knowledge of Him they worship, are called thereto to know not that the Creator of all things is one only, the One true God, but that He is a Father and has begotten a Son; and moreover, and yet more than all this, to gaze attentively on Him in His unchangeable Likeness, that is, the Son. For through the lineaments of that which is modelled, we can readily attain to perfect knowledge of the model. Very necessary then was it, for our Lord Jesus Christ to tell us, that those who have been called through faith to sonship and eternal life, not only ought to learn that the true God is One only, but that He is also a Father; and is the Father of One Who became flesh for our sakes, and Who was sent to restore the corrupted nature of rational beings, that is, of mankind.
