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. [1]

Footnotes

1 - "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.

But ye have an unction from the Holy One - The apostle in this verse evidently intends to say that he had no apprehension in regard to those to whom he wrote that they would thus apostatize, and bring dishonor on their religion. They had been so anointed by the Holy Spirit that they understood the true nature of religion, and it might be confidently expected that they would persevere. The word "unction" or "anointing" (χρίσμα chrisma) means, properly, "something rubbed in or ointed;" oil for anointing, "ointment;" then it means an anointing. The allusion is to the anointing of kings and priests, or their inauguration or coronation, (1-Samuel 10:1; 1-Samuel 16:13; Exodus 28:41; Exodus 40:15; compare the notes at Matthew 1:1); and the idea seems to have been that the oil thus used was emblematic of the gifts and graces of the Holy Spirit as qualifying them for the discharge of the duties of their office. Christians, in the New Testament, are described as "kings and priests," Revelation 1:6; Revelation 5:10, and as a "royal priesthood" 1-Peter 2:5, 1-Peter 2:9; and hence they are represented as "anointed," or as endowed with those graces of the Spirit, of which anointing was the emblem. The phrase "the Holy One" refers here, doubtless, to the Holy Spirit, that Spirit whose influences are imparted to the people of God, to enlighten, to sanctify, and to comfort them in their trials. The particular reference here is to the influences of that Spirit as giving them clear and just views of the nature of religion, and thus securing them from error and apostasy.
And ye know all things - That is, all things which it is essential that you should know on the subject of religion. See the John 16:13 note; 1-Corinthians 2:15 note. The meaning cannot be that they knew all things pertaining to history, to science, to literature, and to the arts; but that, under the influences of the Holy Spirit, they had been made so thoroughly acquainted with the truths and duties of the Christian religion, that they might be regarded as safe from the danger or fatal error. The same may be said of all true Christians now, that they are so taught by the Spirit of God, that they have a practical acquaintance with what religion is, and with what it requires, and are secure from falling into fatal error. In regard to the general meaning of this verse, then, it may he observed:
I. That it does not mean any one of the following things:
(1) That Christians are literally instructed by the Holy Spirit in all things, or that they literally understand all subjects. The teaching, whatever it may be, refers only to religion.
(2) it is not meant that any new faculties of mind are conferred on them, or any increased intellectual endowments, by their religion. It is not a fact that Christians, as such, are superior in mental endowments to others; nor that by their religion they have any mental traits which they had not before their conversion. Paul, Peter, and John had essentially the same mental characteristics after their conversion which they had before; and the same is true of all Christians.
(3) it is not meant that any new truth is revealed to the mind by the Holy Spirit. All the truth that is brought before the mind of the Christian is to be found in the Word of God, and "revelation," as such, was completed when the Bible was finished.
(4) it is not meant that anything is perceived by Christians which they had not the natural faculty for perceiving before their conversion, or which other people have not also the natural faculty for perceiving. The difficulty with people is not a defect of natural faculties, it is in the blindness of the heart.
II. The statement here made by John "does" imply, it is supposed, the following things:
(1) That the minds of Christians are so enlightened that they have a new perception of the truth. They see it in a light in which they did not before. They see it as truth. They see its beauty, its force, its adapted less to their condition and wants. They understand the subject of religion better than they once did, and better than others do. What was once dark appears now plain; what once had no beauty to their minds now appears beautiful; what was once repellant is now attractive.
(2) they see this to be true; that is, they see it in such a light that they cannot doubt that it is true. They have such views of the doctrines of religion, that they have no doubt that they are true, and are willing on the belief of their truth to lay down their lives, and stake their eternal interests.
(3) their knowledge of truth is enlarged. They become acquainted with more truths than they would have known if they had not been under the teaching of the Holy Spirit. Their range of thought is greater; their vision more extended, as well as more clear.
III. The evidence that this is so is found in the following things:
(1) The express statements of Scripture. See 1-Corinthians 2:14-15, and the notes at that passage. Compare John 16:13-14.
(2) it is a matter of fact that it is so.
(a) People by nature do not perceive any beauty in the truths of religion. They are distasteful to them, or they are repulsive and offensive. "The doctrine of the cross is to the Jew a stumbling-block, and to the Greek foolishness." They may see indeed the force of an argument, but they do not see the beauty of the way of salvation.
(b) When they are converted they do. These things appear to them to be changed, and they see them in a new light, and perceive a beauty in them which they never did before.
(c) There is often a surprising development of religious knowledge when persons are converted. They seem to understand the way of salvation, and the whole subject of religion, in a manner and to an extent which cannot be accounted for, except on the supposition of a teaching from above.
(d) This is manifest also in the knowledge which persons otherwise ignorant exhibit on the subject of religion. With few advantages for education, and with no remarkable talents, they show an acquaintance with the truth, a knowledge of religion, an ability to defend the doctrines of Christianity, and to instruct others in the way of salvation, which could have been derived only from some source superior to themselves. Compare John 7:15; Acts 4:13.
(e) The same thing is shown by their "adherence to truth" in the midst of persecution, and simply because they perceive that for which they die to be the truth. And is there anything incredible in this? May not the mind see what truth is? How do we judge of an axiom in mathematics, or of a proposition that is demonstrated, but by the fact that the mind "perceives" it to be true, and cannot doubt it? And may it not be so in regard to religious truth - especially when that truth is seen to accord with what we know of ourselves, our lost condition as sinners, and our need of a Saviour, and when we see that the truths revealed in the Scriptures are exactly adapted to our wants?
(See also the supplementary note under 1-Corinthians 2:14.)

But ye have an unction - The word χρισμα signifies not an unction, but an ointment, the very thing itself by which anointing is effected; and so it was properly rendered in our former translations. Probably this is an allusion to the holy anointing oil of the law, and to Psalm 14:7 : God hath anointed thee with the oil of gladness - he hath given thee the plenitude of the Spirit, which none of thy fellows - none of the prophets, ever received in such abundance. By this it is evident that not only the gifts of the Spirit, but the Holy Spirit himself, is intended. This Spirit dwelt at that time in a peculiar manner in the Church, to teach apostles, teachers, and all the primitive believers, every thing requisite for their salvation; and to make them the instruments of handing down to posterity that glorious system of truth which is contained in the New Testament. As oil was used among the Asiatics for the inauguration of persons into important offices, and this oil was acknowledged to be an emblem of the gifts and graces of the Holy Spirit, without which the duties of those offices could not be discharged; so it is put here for the Spirit himself, who presided in the Church, and from which all gifts and graces flowed. The χρισμα, chrism or ointment here mentioned is also an allusion to the holy anointing ointment prescribed by God himself, Exodus 30:23-25, which was composed of fine myrrh, sweet cinnamon, sweet calamus, cassia lignea, and olive oil. This was an emblem of the gifts and graces of the Divine Spirit. See the notes on Exodus 30:23-25 (note). And for the reason of this anointing see the note on Exodus 29:7.
Ye know all things - Every truth Of God necessary to your salvation and the salvation of man in general, and have no need of that knowledge of which the Gnostics boast.
But although the above is the sense in which this verse is generally understood, yet there is reason to doubt its accuracy. The adjective παντα, which we translate all things, is most probably in the accusative case singular, having ανθρωπον, man, or some such substantive, understood. The verse therefore should be translated: Ye have an ointment from the Holy One, and ye know or discern Every Man. This interpretation appears to be confirmed by των πλανωντων in 1-John 2:26, those who are deceiving or misleading you; and in the same sense should παντων, 1-John 2:27, be understood: But as the same anointing teacheth you παντων, not of all things, but of All Men. It is plain, from the whole tenor of the epistle, that St. John is guarding the Christians against seducers and deceivers, who were even then disturbing and striving to corrupt the Church. In consequence of this he desires them to try the spirits whether they were of God, 1-John 4:1. But how were they to try them? Principally by that anointing - that spiritual light and discernment which they had received from God; and also by comparing the doctrine of these men with what they had heard from the beginning. The anointing here mentioned seems to mean the spirit of illumination, or great knowledge and discernment in spiritual things. By this they could readily distinguish the false apostles from the true.

(21) But ye have an (p) unction from the (q) Holy One, and ye know all things.
(21) Thirdly, he comforts them, to make them stand fast, as they are anointed by the Holy Spirit with the true knowledge of salvation.
(p) The grace of the Holy Spirit, and this is a borrowed type of speech taken from the anointings used in the law.
(q) From Christ who is peculiarly called Holy.

But ye have an unction from the Holy One,.... Meaning the Spirit, and his graces, with which Christ, the head, is anointed without measure, and his members in measure; from whence he is called Christ, and they Christians. These were really the Lord's anointed ones; they were true believers; were the wise virgins who had oil in their vessels with their lamps, which would never go out. The grace of the Spirit is called a chrism, or an ointment, or an anointing, in allusion to the anointing oil under the law; See Gill on Matthew 25:3; of which anointing oil the Jews say (h), that it continues all of it, "to time to come", (i.e. to the times of the Messiah,) as it is said, Exo_30:31. Now this these saints had, "from the Holy One"; or that Holy One; meaning, not the Holy Spirit of God, though it is true that this anointing, or these graces, were from him; he is the author of them, and may truly be said to anoint with them; nor the Father, who is holy in his nature, and in his works, and is the God of all grace, and is said to anoint the saints too, 2-Corinthians 1:21, but rather the Lord Jesus Christ, who is holy, both as God and man, and from whose fulness all grace is had. This oil, or ointment, was first poured on him without measure, and from him it descends to all the members of his mystical body, as the ointment poured on Aaron's head descended to his beard, and to the skirts of his garments; see 1-John 2:27;
and ye know all things; for this anointing is a teaching one; it makes persons of quick understanding; it enlightens their understandings, refreshes their memories, and strengthens all the powers and faculties of the soul; it leads into the knowledge of all spiritual things, into all the mysteries of grace, and truths of the Gospel, into all things necessary for salvation; for these words are not to be taken in the largest sense, in which they are only applicable to the omniscient God, but to be restrained to the subject matter treated of, and to those things chiefly in which the antichrists and deceivers cited; and regard not a perfect knowledge, for those that know most of these things, under the influence of this unction, know but in part. The Syriac version reads, "all men", and so refers to that discerning of spirits, of the Spirit of truth, from the spirit of error; a gift which was bestowed on many in the primitive times, by which they could distinguish hypocrites from true believers, and antichrists and deceivers from the faithful ministers of the word. One of Stephens's copies reads, "and ye all know".
(h) T. Hieros. Horayot, fol. 47. 3.

But--Greek, "And." He here states the means which they as believers have wherewith to withstand. Antichrists (1-John 2:18), namely, the chrism (so the Greek: a play upon similar sounds), or "anointing unguent," namely, the Holy Spirit (more plainly mentioned further on, as in John's style, 1-John 3:24; 1-John 4:13; 1-John 5:6), which they ("ye" is emphatical in contrast to those apostates, 1-John 2:19) have "from the Holy One, Christ" (John 1:33; John 3:34; John 15:26; John 16:14): "the righteous" (1-John 2:1), "pure" (1-John 3:3), "the Holy One" (Acts 3:14) "of God"; Mark 1:24. Those anointed of God in Christ alone can resist those anointed with the spirit of Satan, Antichrists, who would sever them from the Father and from the Son. Believers have the anointing Spirit from the Father also, as well as from the Son; even as the Son is anointed therewith by the Father. Hence the Spirit is the token that we are in the Father and in the Son; without it a man is none of Christ. The material unguent of costliest ingredients, poured on the head of priests and kings, typified this spiritual unguent, derived from Christ, the Head, to us, His members. We can have no share in Him as Jesus, except we become truly Christians, and so be in Him as Christ, anointed with that unction from the Holy One. The Spirit poured on Christ, the Head, is by Him diffused through all the members. "It appears that we all are the body of Christ, because we all are anointed: and we all in Him are both Christ's and Christ, because in some measure the whole Christ is Head and body."
and--therefore.
ye know all things--needful for acting aright against Antichrist's seductions, and for Christian life and godliness. In the same measure as one hath the Spirit, in that measure (no more and no less) he knows all these things.

But ye have an anointing - A chrism; perhaps so termed in opposition to the name of antichrist; an inward teaching from the Holy Ghost, whereby ye know all things - Necessary for your preservation from these seducers, and for your eternal salvation. St. John here but just touches upon the Holy Ghost, of whom he speaks more largely, 1-John 3:24; 1-John 4:13; 1-John 5:6.