44 Jesus cried and said, He that believeth on me, believeth not on me, but on him that sent me.
[AD 220] Tertullian on John 12:44
It is through the Son that one believes in the Father, while the Father also is the authority from which springs belief in the Son.

[AD 220] Tertullian on John 12:44
"Then again, Jesus exclaims, and says, He that believeth on me, believeth not on me, but on Him that sent me; " because it is through the Son that men believe in the Father, while the Father also is the authority whence springs belief in the Son.

[AD 397] Ambrose of Milan on John 12:44
The one who confesses the Father believes on the Son. For the one who does not know the Son does not know the Father. For everyone that denies the Son does not have the Father, but the one who confesses the Son has both the Father and the Son. What, then, is the meaning of “believes not in me”? It speaks not about what you can perceive in bodily form, nor merely on the man whom you see. For he has stated that we are to believe not merely on a man, but that you may believe that Jesus Christ himself is both God and man. This is why, for both reasons, he says, “I came not from myself.” And again: “I am the beginning, of which also I speak to you.”

[AD 407] John Chrysostom on John 12:44-50
(Hom. lxviii. 1) Because the love of human praise prevented the chief rulers from believing, Jesus cried and said, He that believeth on Me, believeth not on Me, but on Him that sent Me: as if to say, Why are ye afraid to believe on Me? Your faith through Me passes to God.

(Hom. lxix. 1) He that believeth on Me, believeth not on Me, but on Him that sent Me: as if He said, He that taketh water from a stream, taketh the water not of the stream, but of the fountain. Then to show that it is not possible to believe on the Father, if we do not believe on Him, He says, He that seeth Me, seeth Him that sent Me. What then? Is God a body? By no means; seeing here is the mind's vision. What follows still further shows His union with the Father. I am come a light into the world. This is what the Father is called in many places. He calls Himself the light, because he delivers from error, and disperses the darkness of the understanding; that whosoever believeth in Me should not abide in darkness.

(Hom. lxix. 1) And to show that He does not let His despisers go unpunished, from want of power, He adds, And if any man hear My words and believe not, I judge him not.

(Hom. lxix. 2) But that this might not serve to encourage sloth, He warns men of a terrible judgment coming; He that rejecteth Me, and heareth not My words, hath one that judgeth him.

(Hom. lxviii. 2) Or, I judge him not, i. e. I am not the cause of his destruction, but he is himself, by despising my words. The words that I have just said, shall be his accusers, and deprive him of all excuse; the word that I have spoken, the same shall judge him. And what word? This, viz. thatf I have not spoken of Myself, but the Father which sent Me gave Me a commandment what I should say, and what I should speak. All these things were said on their account, that they might have no excuse.

[AD 407] John Chrysostom on John 12:44
As though He had said, Why fear ye to believe in Me? Faith passes to the Father through Me, as does also unbelief. See how in every way He shows the unvaryingness of His Essence. He said not, He that believes Me, lest any should assert that He spoke concerning His words; this might have been said in the case of mere men, for he that believes the Apostles, believes not them, but God. But that you might learn that He speaks here of the belief on His Essence, He said not, He that believes My words, but, He that believes in Me. And wherefore, says some one, has He nowhere said conversely, He that believes in the Father, believes not on the Father but on Me? Because they would have replied, Lo, we believe in the Father, but we believe not on you. Their disposition was as yet too infirm. Anyhow, conversing with the disciples, He did speak thus: You believe in the Father, believe also on Me John 14:1; but seeing that these then were too weak to hear such words, He leads them in another way, showing that it is not possible to believe in the Father, without believing on Him. And that you may not deem that the words are spoken as of man, He adds,
[AD 430] Augustine of Hippo on John 12:44-50
(Tr. liii. 13) As their faith grew, their love of human praise grew still more, and outstripped it.

(Tr. liv. 2) He signifies to them that He is more than He appears to be, (for to men He appeared but a man; His Godhead was hid.) Such as the Father is, such am I in nature and in dignity; He that believeth on Me, believeth not on Me, i. e. on that which He sees, but on Him that sent Me, i. e. on the Father. [1He that believes in the Father must believe in Him as the Father, i. e. must believe that He has a Son; and reversely, he who believes in the Son thereby believes in the Father.] And again, if any one thinks that God has sons by grace, but not a Son equal and coeternal with Himself, neither does he believe 2on the Father, who sent the Son; because what he believes on is not the Father who sent Him. (c. 3.). And to show that He is not the Son, in the sense of one out of many, a son by grace, but the Only Son equal to the Father, He adds, And He that seeth Me, seeth Him that sent Me; so little difference is there between Me and Him that sent Me, that He that seeth Me, seeth Him. Our Lord sent His Apostles, yet none of them dared to say, He that believeth on Me. We believe an Apostle, but we do not believe on an Apostle. Whereas the Only Begotten says, He that believeth on Me, doth not believe on Me, but on Him that sent Me. Wherein He does not withdraw the believer's faith from Himself, but gives him a higher object than the form of a servant, for that faith.

(Tr. liv. 4) Whereby it is evident, that He found all in darkness. In which darkness if they wish not to remain, they must believe in the light which is come into the world. He says in one place to His disciples, Ye are the light of the world; but He did not say to them, Ye are come a light into the world, that whosoever believeth on you should not abide in darkness. All saints are lights, but they are so by faith, because they are enlightened by Him, from Whom to withdraw is darkness.

(Tr. liv. 5, 6) i. e. I judge him not now. He does not say, I judge him not at the last day, for that would be contrary to the sentence above, The Father hath committed all judgment unto the Son. (5:22) And the reason follows, why He does not judge now; For I came not to judge the world, but to save the world. Now is the time of mercy, afterward will be the time of judgment.

(Tr. liv. 6) Mean time they waited to know who this one was; so He proceeds: The word that I have spoken, the same shall judge him at the last day. He makes it sufficiently clear that He Himself will judge at the last day. For the word that He speaks, is Himself. He speaks Himself, announces Himself. We gather too from these words that those who have not heard, will be judged differently from those who have heard and despised.

(i. de Trin. c. xii. [26.]) I judge him not; the word that I have spoken shall judge him: for I have not spoken of Myself. The word which the Son speaks judges, because the Son did not speak of Himself: for I have nut spoken of Myself: i. e. I was not born of Myself.

AUGUSTINE.e I ask then how we shall understand this, I will not judge, but the word which I have spoken will judge? Yet He Himself is the Word of the Father which speaketh. Is it thus? I will not judge by My human power, as the Son of man, but as the word of God, because I am the Son of God.

(Tr. liv. 7) When the Father gave the Son a commandment, He did not give Him what He had not: for in the Wisdom of the Father, i. e. in the Word, are all the commandments of the Father. The commandment is said to be given, because it is not from him to whom it is said to be given. But to give the Son that which He never was without, is the same as to beget the Son who never was not.

(Tr. liv) If life everlasting is the Son Himself, and the commandment is life everlasting, what is this but saying, I am the commandment of the Father? And in the same way in the following; Whatsoever I speak therefore, even as the Father said unto Me, so I speak, we must not understand, said unto Me, as if words were spoken to the Only Word. The Father spoke to the Son, as He gave life to the Son; not that the Son knew not, or had not, but that He was the Son. What is meant by, as He said unto Me, so I speak, but that I am the Word who speaks. The Father is true, the Son is truth: the True, begat the Truth. What then could He say to the Truth, if the Truth was perfect from the beginning, and no new truth could be added to Him? That He spake to the Truth then, means that He begat the Truth.

[AD 430] Augustine of Hippo on John 12:44
1. Whilst our Lord Jesus Christ was speaking among the Jews, and giving so many miraculous signs, some believed who were foreordained to eternal life, and whom He also called His sheep; but some did not believe, and could not believe, because that, by the mysterious yet not unrighteous judgment of God, they had been blinded and hardened, because forsaken of Him who resists the proud, but gives grace unto the humble. James 4:6 But of those who believed, there were some whose confession went so far, that they took branches of palm trees, and met Him as He approached, turning in their joy that very confession into a service of praise: while there were others, belonging to the chief rulers, who had not the boldness to confess their faith, lest they should be put out of the synagogue; and whom the evangelist has branded with the words, that they loved the praise of men more than the praise of God John 12:43. Of those also who did not believe, there were some who would afterwards believe, and whom He foresaw, when He said, When you have lifted up the Son of man, then shall you acknowledge that I am He: but there were some who would remain in the same unbelief, and be imitated by the Jewish nation of the present day, which, being shortly afterwards crushed in war, according to the prophetic testimony which was written concerning Christ, has since been scattered almost through the whole world.

2. While matters were in this state, and His own passion was now at hand, Jesus cried, and said, as our lesson today commences, He that believes in me, believes not on me, but on Him that sent me; and he that sees me, sees Him that sent me. He had already said in a certain place, My doctrine is not mine, but His that sent me. Where we understood that He called His doctrine just what He is Himself, the Word of the Father; and in saying, My doctrine is not mine, but His that sent me, implied this, that He was not of Himself, but had His being from another. For He was God of God, the Son of the Father: but the Father is not God of God, but God, the Father of the Son. And now when He says, He that believes in me, believes not on me, but on Him that sent me, how else are we to understand it, but that He appeared as man to men, while He remained invisible as God? And that none might think that He was no more than what they saw of Him, He indicated His wish to be believed on, as equal in character and rank with the Father, when He said, He that believes in me, believes not on me, that is, merely on what he sees of me, but on Him that sent me, that is, on the Father. But he that believes in the Father, must believe that He is the Father; and he that believes in Him as the Father, must believe that He has a Son; and in this way, he that believes in the Father, must believe in the Son. But let no one believe about the only-begotten Son just what they believe about those who are called the sons of God by grace and not by nature, as the evangelist says, He gave them power to become the sons of God, and according to what the Lord Himself also mentioned, as declared in the law, I said, You are gods; and all of you children of the Most High: because He said, He that believes in me, believes not on me, to show that the whole extent of our faith in Christ should not be limited by His manhood. He therefore, He says, believes in me, who does not believe in me merely according to what he sees of me, but on Him that sent me: so that, believing thus on the Father, he may believe that He has a Son co-equal with Himself, and then attain to a true faith in me. For if one should think that He has sons only according to grace, who are certainly no more than His creatures, and not the Word, but those made by the Word, and that He has no Son co-equal and co-eternal with Himself, ever born, alike incommutable, in nothing dissimilar and inferior, then he believes not on the Father who sent Him, for the Father who sent Him is no such conception as this.

3. And, accordingly, after saying, He that believes in me, believes not on me, but on Him that sent me, that it might not be thought that He would have the Father so understood, as if He were the Father only of many sons regenerated by grace, and not of the only-begotten Word, His own co-equal, He immediately added, And he that sees me, sees Him that sent me. Does He say here, He that sees me, sees not me, but Him that sent me, as He had said, He that believes me, believes not on me, but on Him that sent me? For He uttered the former of these words, that He might not be believed on merely as He then appeared, that is, as the Son of man; and the latter, that He might be believed on as the equal of the Father. He that believes in me, believes not merely on what He sees of me, but believes in Him that sent me. Or, when he believes in the Father, who begot me, His own co-equal, let him believe in me, not as he sees me, but as [he believes] on Him that sent me; for so far does the truth, that there is no distance between Him and me, reach, that He who sees me, sees Him that sent me. Certainly, Christ the Lord Himself sent His apostles, as their name implies: for as those who in Greek are called angeli are in Latin called nuntii [messengers], so the Greek apostoli [apostles] becomes the Latin missi [persons sent]. But never would any of the apostles have dared to say, He that believes in me, believes not on me, but on Him that sent me; for in no sense whatever would he say, He that believes in me. We believe an apostle, but we do not believe in him; for it is not an apostle that justifies the ungodly. But to him that believes in Him that justifies the ungodly, his faith is counted for righteousness. Romans 4:5 An apostle might say, He that receives me, receives Him that sent me; or, He that hears me, hears Him that sent me; for the Lord tells them so Himself: He that receives you, receives me; and he that receives me, receives Him that sent me. Matthew 10:40 For the master is honored in the servant, and the father in the son: but then the father is as it were in the son, and the master as it were in the servant. But the only-begotten Son could rightly say, Believe in God, and believe in me; as also what He says here, He that believes in me, believes not on me, but on Him that sent me. He did not turn away the faith of the believer from Himself, but only would not have the believer continue in the form of a servant: because every one who believes in the Father that sent Him, straightway believes in the Son, without whom he knows that the Father has no existence as such, and thus reaches in his faith to the belief of His equality with the Father, in conformity with the words that follow, And he that sees me, sees Him that sent me.

4. Attend to what follows: I have come a light into the world, that whosoever believes in me should not abide in darkness. He said in a certain place to His disciples, You are the light of the world. A city that is set on a hill cannot be hid. Neither do men light a candle, and put it under a bushel, but on a candlestick; that it may give light to all that are in the house: so let your light shine before men, that they may see your good works, and glorify your Father who is in heaven: Matthew 5:14-16 but He did not say to them, You have come a light into the world, that whosoever believes in you should not abide in darkness. Such a statement, I maintain, can nowhere be met with. All the saints, therefore, are lights, but they are illuminated by Him through faith; and every one that becomes separated from Him will be enveloped in darkness. But that Light, which enlightens them, cannot become separated from itself; for it is altogether beyond the reach of change. We believe, then, the light that has thus been lit, as the prophet or apostle: but we believe him for this end, that we may not believe in that which is itself enlightened, but, with him, on that Light which has given him light; so that we, too, may be enlightened, not by him, but, along with him, by the same Light as he. And when He says, That whosoever believes in me may not abide in darkness, He makes it sufficiently manifest that all have been found by Him in a state of darkness: but that they may not abide in the darkness wherein they have been found, they ought to believe in that Light which has come into the world, for thereby was the world created.

5. And if any man, He says, hear my words, and keep them not, I judge him not. Remember what I know you have heard in former lessons; and if any of you have forgotten, recall it: and those of you who were absent then, but are present now, hear how it is that the Son says, I judge him not, while in another place He says, The Father judges no man, but has committed all judgment unto the Son; namely, that thereby we are to understand, It is not now that I judge him. And why not now? Listen to the sequel: For I am not come, He says, to judge the world, but to save the world; that is, to bring the world into a state of salvation. Now, therefore, is the season of mercy, afterwards will be the time for judgment: for He says, I will sing to You, O Lord, of mercy and judgment.

6. But see also what He says of that future judgment in the end: He that despises me, and receives not my words, has one that judges him: the word that I have spoken, the same shall judge him in the last day. He says not, He that despises me, and receives not my words, I judge him not at the last day; for had He said so, I do not see how it could have been else than contradictory of that other statement, when He says, The Father judges no man, but has committed all judgment unto the Son. But when He said, He that despises me, and receives not my words, has one to judge him, and, for the information of those who were waiting to hear who that one was, went on to add, The word that I have spoken, the same shall judge him in the last day, He made it sufficiently manifest that He Himself would then be the judge. For it was of Himself He spoke, Himself He announced, and Himself He set forth as the gate whereby He entered as the Shepherd to His sheep. In one way, therefore, will those be judged who have never heard that word, in another way those who have heard and despised. For as many as have sinned without law, says the apostle, shall also perish without law; and as many as have sinned in the law, shall be judged by the law. Romans 2:12

7. For I have not, He says, spoken of myself. He says that He has not spoken of Himself, because He is not of Himself. Of this we have frequently discoursed already; so that now, without any more instruction, we have simply to remind you of it as a truth with which you are familiar. But the Father who sent me, He gave me a commandment what I should say, and what I should speak. We would not stay to elaborate this, did we know that we were now speaking with those with whom we have spoken on former occasions, and of these, not with all, but such only whose memories have retained what they heard: but because there are perhaps some now present who did not hear, and some in a similar condition who have forgotten what they heard, on their account let those who remember what they have heard bear with our delay. How gives the Father a commandment to His only Son? With what words does He speak to the Word, seeing that the Son Himself is the only-begotten Word? Could it be by an angel, seeing that by Him the angels were created? Was it by means of a cloud, which, when it gave forth its sound to the Son, gave it not on His account, as He Himself also tells us elsewhere, but for the sake of others who were needing to hear it John 12:29? Could it be by any sound issuing from the lips, where bodily form was wanting, and where there is no such local distance separating the Son from the Father as to admit of any intervening air, to give effect, by its percussion, to the voice, and render it audible? Let us put away all such unworthy notions of that incorporeal and ineffable subsistence. The only Son is the Word and the Wisdom of the Father, and therein are all the commandments of the Father. For there was no time that the Son knew not the Father's commandment, so as to make it necessary for Him to possess in course of time what He possessed not before. For what He has received from the Father, He received in being born, and was given it in being begotten. For the life He is, and life He certainly received in being born, while yet there was no antecedent time when life was wanting to His personal existence. For, on the one hand, the Father has life, and is what He has: and yet He received it not, because He is not of any one. But the Son received life as the Father's gift, of whom He is: and so He Himself is what He has; for He has life, and is the life. Listen to Himself when He says, As the Father has life in Himself, so has He given to the Son to have life in Himself. Could He give it to one who was in being, and yet hitherto was destitute thereof? On the contrary, in the very begetting it was given by Him who begot the life, and so life begot the life. And to show that He begot the life equal, and not inferior to Himself, it was said, As He has life in Himself, so has He also given to the Son to have life in Himself. He gave life; for in begetting the life, what was it He gave Him, save to be the life? And as His nativity is itself eternal, there never was a time without that Son who is the life, and never was there a time when the Son Himself was without the life; and as His nativity is eternal, so He, who was thus born, is eternal life. And so the Father gave not to the Son a commandment which He had not already; but, as I said, in the Wisdom of the Father, that is, in the word of the Father, are laid up all the Father's commandments. And yet the commandment is said to have been given Him, because He, to whom it is thus given, is not of Himself: and to give that to the Son which He never was without, is the same in meaning as to beget that Son who never was without existence.

8. There follow the words: And I know that His commandment is life everlasting. If, then, the Son Himself is eternal life, and the Father's commandment the same, what else is expressed than this, I am the Father's commandment? And in like manner, in what He proceeds to say, Whatsoever I speak, even as the Father said unto me, so I speak, let us not be taking the said unto me as if the Father used words in speaking to the only Word, or that the Word of God needed words from God. The Father spoke to the Son in the same way as He gave life to the Son; not that He knew not the one, or had not the other, but just because He was the Son. What, then, do the words mean, Even as He said unto me, so I speak; but just, I speak the truth? So the former said as the Truthful One what the latter thus spoke as the Truth. The Truthful begot the Truth. What, then, could He now say to the Truth? For the Truth had no imperfection to be supplied by additional truth. He spoke, therefore, to the Truth, because He begot the Truth. And in like manner the Truth Himself speaks what has been said to Him; but only to those who have understanding, and who are taught by Him as the God-begotten Truth. But that men might believe what they had not yet capacity to understand, words that were audible issued from His human lips; sounds passing rapidly away broke on the ear, and speedily completed the little term of their duration: but the truths themselves, of which the sounds are but signs, passed, as it were, into the memory of those who heard them, and have come down to us also by means of written characters as signs addressed to the eye. But it is not thus that the Truth speaks; He speaks inwardly to the souls of the intelligent; He needs no sound to instruct, but floods the mind with the light of understanding. And he, then, who in that light is able to behold the eternity of His birth, himself hears in the same way the Truth speaking, as He heard the Father telling Him what He should speak. He has awakened in us a great longing for that sweet experience of His presence within; but it is by daily growth that we acquire it; it is by walking that we grow, and it is by forward efforts we walk, so as to be able at last to attain it.
[AD 430] Augustine of Hippo on John 12:44
What is this we have just heard, brothers and sisters: the Lord saying, “Whoever believes in me does not believe in me, but in the one who sent me”? It is good for us to believe in Christ, especially since he himself also said quite plainly what you heard just now, that is, that he had come as light into the world, and that whoever believes in him will not walk in darkness but will have the light of life.So it is good to believe in Christ. It is a great good to believe in Christ and a great evil not to believe in Christ. But because Christ the Son is whatever he is from the Father, while the Father is not from the Son but is the Father of the Son, that is why the Son does indeed call for faith in himself but refers the honor of it to his only-begetter.

[AD 444] Cyril of Alexandria on John 12:44
Contrary to His wont He cries aloud, and the cry convicts the ill-timed fear of men which influenced those who believed on Him and yet veiled their belief. For He wishes to be honoured of men that choose to admire Him, not stealthily, but openly. For He assumed that while faith ought to be laid up in the heart, nevertheless the most wise confession that is founded thereon ought to be made with great boldness. And forasmuch as, being by Nature God, He condescended to take a form like ours, He refuses for the time to declare in plain words into the ears of men who hate Him that they ought to believe in Him, although He often did say this; and with fullest adaptation to the needs of those who suffer the distemper of untamable envy at Him, He gradually accustoms their minds to penetrate towards the depth of the mysteries concerning Himself, [leading them] not to the Human Person, but to That Which was of the Divine Essence; inasmuch as the Godhead is apprehended completely in the Person of God the Father, for He, hath in Himself the Son and the Spirit. Exceeding wisely He carries them onwards, saying: He that believeth on Me believeth not on Me, but on Him that sent Me; for He does not exclude Himself from being believed on by us, because He is God by nature and has shone forth from God the Father. But skilfully (as has been said) He handles the mind of the weak to mould them to piety, in order that thou mightest understand Him to say something of this kind: "When ye believe on Me, Who for your sakes am on the one hand a man like yourselves, but on the other hand am God by reason of My own Nature and of the Father from Whom I am, do not suppose that it is upon a man you are setting your faith. For I am by Nature God, notwithstanding that I appear like one of yourselves, and I have within Myself Him Who begat Me. Forasmuch therefore as I am Consubstantial with Him that hath begotten Me, your faith will assuredly pass on also to the Father Himself." As we said therefore, the Lord, gradually training them to something better, and profitably interweaving the human with what is God-befitting, said: He that believeth on Me and the words that follow. For that the faith must not be directed simply to a man, but to the Nature of God, notwithstanding that the Word was clothed in flesh, because His Nature was not converted into man, He hath very clearly informed us; and that He is on an equality in every respect with God the Father, by reason of Their likeness of Nature and Their identity (as we may term it) of Essence, He made amply clear: by saying:----
[AD 1107] Theophylact of Ohrid on John 12:44-50
Since the Son is the Word of the Father, and reveals completely what is in the mind of the Father, He says He receives a commandment what He should say, and what He should speak: just as our word, if we say what we think, brings out what is in our minds.
And I know that His commandment is life everlasting.