1 John 2:20-23
20. But ye have an unction from the Holy One, and ye know all things.
20. Et vos unctionem habetis a Sancto, et novistis omnia.
21. I have not written unto you because ye know not the truth, but because ye know it, and that no lie is of the truth.
21. Non scripsi vobis, quia non noveritis veritatem; sed quia novistis eam, et quia omne mendacium ex veritate non est.
22. Who is a liar but he that denieth that Jesus is the Christ? He is antichrist, that denieth the Father and the Son.
22. Quis est mendax, nisi qui negat Jesum esse Christum? Hic est antichristus, qui negat Patrem et Filium.
23. Whosoever denieth the Son, the same hath not the Father: (but) he that acknowledgeth the Son hath the Father also.
23. Omnis qui negat Filium, neque Patrem habet.
20 But ye have an unction. The Apostle modestly excuses himself for having so earnestly warned them, lest they should think that they were indirectly reproved, as though they were rude and ignorant of those things which they ought to have well known. So Paul conceded wisdom to the Romans, that they were able and fit to admonish others. He at the same time shewed that they stood in need of being reminded, in order that they might rightly perform their duty. (Romans 15:14, 15.) The Apostles did not, however, speak thus in order to flatter them; but they thus wisely took heed lest their doctrine should be rejected by any, for they declared what was suitable and useful, not only to the ignorant, but also to those well instructed in the Lord's school.
Experience teaches us how fastidious the ears of men are. Such fastidiousness ought indeed to be far away from the godly; it yet behooves a faithful and wise teacher to omit nothing by which he may secure a hearing from all. And it is certain that we receive what is said with less attention and respect, when we think that he who speaks disparages the knowledge which has been given us by the Lord. The Apostle by this praise did at the same time stimulate his readers, because they who were endued with the gift of knowledge, had less excuse if they did not surpass others in their proficiency.
The state of the case is, that the Apostle did not teach them as though they were ignorant, and acquainted only with the first elements of knowledge, but reminded them of things already known, and also exhorted them to rouse up the sparks of the Spirit, that a full brightness might shine forth in them. And in the next words he explained himself, having denied that he wrote to them because they knew not the truth, but because they had been well taught in it; for had they been wholly ignorant and novices, they could not have comprehended his doctrine.
Now, when he says that they knew all things, it is not to be taken in the widest sense, but ought to be confined to the subject treated of here. But when he says that they had an unction from the Holy One, he alludes, no doubt, to the ancient types. The oil by which the priests were anointed was obtained from the sanctuary; and Daniel mentions the coming of Christ as the proper time for anointing the Most Holy. (Daniel 9:24.) For he was anointed by the Father, that he might pour forth on us a manifold abundance from his own fullness. It hence follows that men are not rightly made wise by the acumen of their own minds, but by the illumination of the Spirit; and further, that we are not otherwise made partakers of the Spirit than through Christ, who is the true sanctuary and our only high priest. 
21 And that no lie is of the truth. He concedes to them a judgment, by which they could distinguish truth from falsehood; for it is not the dialectic proposition, that falsehood differs from truth, (such as are taught as general rules in the schools;) but what is said is applied to that which is practical and useful; as though he had said, that they did not only hold what was true, but were also so fortified against the impostures and fallacies of the ungodly, that they wisely took heed to themselves. Besides, he speaks not of this or of that kind of falsehood; but he says, that whatever deception Satan might contrive, or in whatever way he might attack them, they would be able readily to distinguish between light and darkness, because they had the Spirit as their guide.
22 Who is a liar He does not assert that they alone were liars who denied that the Son of God appeared in the flesh, lest no one in unloosing the knot should above measure torment himself; but that they surpassed all others, as though he had said, that except this be deemed a lie, no other could be so reckoned; as we are wont commonly to say, "If perfidy towards God and men is not a crime, what else can we call a crime?" 
What he had generally said of false prophets, he now applies to the state of his own time; for he points out, as by the finger, those who disturbed the Church. I readily agree with the ancients, who thought that Cerinthus and Carpocrates are here referred to. But the denial of Christ extends much wider; for it is not enough in words to confess that Jesus is the Christ, except he is acknowledged to be such as the Father offers him to us in the gospel. The two I have named gave the title of Christ to the Son of God, but imagined him to be man only. Others followed them, such as Arius, who, adorning him with the name of God, robbed him of his eternal divinity. Marcion dreamt that he was a mere phantom. Sabellius imagined that he differed nothing from the Father. All these denied the Son of God; for not one of them really acknowledged the true Christ; but, adulterating, as far as they could, the truth respecting him, they devised for themselves an idol instead of Christ. Then broke out Pelagius, who, indeed, raised no dispute respecting Christ's essence, but allowed him to be true man and God; yet he transferred to us almost all the honor that belongs to him. It is, indeed, to reduce Christ to nothing, when his grace and power are set aside.
So the Papists, at this day, setting up freewill in opposition to the grace of the Holy Spirit, ascribing a part of their righteousness and salvation to the merits of works, feigning for themselves innumerable advocates, by whom they render God propitious to them, have a sort of fictitious Christ, I know not what; but the lively and genuine image of God, which shines forth in Christ, they deform by their wicked inventions; they lessen his power, subvert and pervert his office.
We now see that Christ, is denied, whenever those things which peculiarly belong to him, are taken away from him. And as Christ is the end of the law and of the gospel, and has in himself all the treasures of wisdom and knowledge, so he is the mark at which all heretics level and direct their arrows. Therefore the Apostle does not, without reason, make those the chief impostors, who fight against Christ, in whom the full truth is exhibited to us.
He is Antichrist He speaks not of that prince of defection who was to occupy the seat of God; but all those who seek to overthrow Christ, he puts them among that impious band. And that he might amplify their crime, he asserts that the Father, no less than the Son, is denied by them; as though he had said, "They have no longer any religion, because they wholly cast away God." And this he afterwards confirms, by adding this reason, that the Father cannot be separated from the Son.
Now this is a remarkable sentence, and ought to be reckoned among the first axioms of our religion. yea, when we have confessed that there is one true God, this second article ought necessarily to be added, that he is no other but he who is made known in Christ. The Apostle does not here treat distinctly of the unity of essence. It is, indeed, certain, that the Son cannot be disunited from the Father, for he is of the same essence, (homoousios;) but another thing is spoken of here, that is, that the Father, who is invisible, has revealed himself only in his Son. Hence he is called the image of the Father, (Hebrews 1:3,) because he sets forth and exhibits to us all that is necessary to be known of the Father. For the naked majesty of God would, by its immense brightness, ever dazzle our eyes; it is therefore necessary for us to look on Christ. This is to come to the light, which is justly said to be otherwise inaccessible.
I say, again, that there is not here a distinct discussion respecting the eternal essence of Christ, which he has in common with the Father. This passage is, indeed, abundantly sufficient to prove it: but John calls us to this practical part of faith, that as God has given himself to us to be enjoyed only in Christ, he is elsewhere sought for in vain; or (if any one prefers what is clearer) that as in Christ dwells all the fullness of the Deity, there is no God apart from him. It hence follows, that Turks, Jews, and such as are like them, have a mere idol and not the true God. For by whatever titles they may honor the God whom they worship, still, as they reject him without whom they cannot come to God, and in whom God has really manifested himself to us, what have they but some creature or fiction of their own? They may flatter themselves as much as they please, with their own speculations, who, without Christ, philosophize on divine things; it is still certain that they do nothing but rave and rant, because, as Paul says, they hold not the Head. (Colossians 2:19.) It is obvious, hence, to conclude how necessary is the knowledge of Christ.
Many copies have the opposite sentence, "He who confesses the Son," etc. But as I think that a note by some copyist has crept into the text, I hesitated not to omit it.  But if its insertion be approved, the meaning would be, that there is no right confession of God except the Father be acknowledged in the Son.
Were any one to object and say, that many of the ancients thought rightly of God, to whom Christ was not known: I allow that the knowledge of Christ has not been always so explicitly revealed, nevertheless, I contend that it has been always true, that as the light of the sun comes to us by its rays, so the knowledge of God has been communicated through Christ.
 "From the Holy One," from the Father, say some; from the Son, say others; from the Holy Spirit, according to a third party. By comparing this verse with the 27th and the 28th verse, we see reason to conclude that the "Holy One" is Christ, who had promised the Spirit to teach his people. The unction, or the anointing, is the act of the Spirit by which the truth is taught. -- Ed.  Taking this view of the passage, we may give this rendering, -- "Who is a liar, except it be he who denies that Jesus is the Christ?" -- Ed.  The words are found in most of the MSS., and in most of the versions, and in many of the Fathers. Besides, they wholly comport with the usual style of the Apostle, whose common practice it was to state things positively and negatively, and vice versa. Sec especially chap. 5:12. -- Ed.
 Taking this view of the passage, we may give this rendering, -- "Who is a liar, except it be he who denies that Jesus is the Christ?" -- Ed.
 The words are found in most of the MSS., and in most of the versions, and in many of the Fathers. Besides, they wholly comport with the usual style of the Apostle, whose common practice it was to state things positively and negatively, and vice versa. Sec especially chap. 5:12. -- Ed.