Believers are said to be anointed, 2 Cor. i. 21; or to have an unction from the Holy One, 1 John ii. 20, and it is added, ver. 27, “The anointing which ye have received, abidith in you. And the same anointing teaches you all things.”
To understand this we may observe, that all persons and things which were dedicated to God under the Old Testament, were anointed with material oil. Kings, priests, and prophets; the sanctuary, the altar, and all the utensils of divine worship were anointed. And all these were typical of what was to come; and had their first, proper, and full accomplishment in the person of Jesus Christ. And because He was to be Most Holy, the spring and cause of all holiness in others, He had His name from hence: for Messiah in the Old Testament, and Christ in the New, are as much as the anointed One. The unction of Christ consisted principally in the full communication of the Spirit unto Him, not by measure, in all His graces and gifts.
Believers have their unction immediately from Christ: “Ye have an unction form the Holy One,” as He is called, Acts iii. 14; Rev, iii. 7; Dan. Ix. 24; and it consists in the communication of the Holy Spirit unto them. It is not the Spirit who anoints us; but He is the unction wherewith we are anointed by the Holy One. And there are two effects ascribed to it. The first is teaching, with a saving, permanent knowledge of the truth thereby produced in our minds.-“Ye have an unction-and ye know all things:”-all the fundamental, essential truths of the gospel; all you need to know, that you may obey God truly, and be saved infallibly. Hence it is called, “the anointing of our eyes with eye-salve that we may see,” Rev. iii. 18; and so it answers to that unction of Christ by the Spirit, which made Him “of quick understanding in the fear of the Lord,” Isa. Xi. 3.
To this also may be referred what is said of believers being made kings and priests, Rev. i. 5: for it is an allusion to anointing such persons of old. Whatever was typical therein, was fully accomplished in the unction of Christ to His office, as the sovereign King, Priest, and Prophet of the Church. Wherefore, by a participation in His unction, they are said to be made kings and priests, or a royal priesthood; for they partake of the same Spirit wherewith He was anointed. Whereas therefore these titles denote the dignity of believers in their special relation to God, by this unction they are particularly dedicated and consecrated to Him.
On this unction depends the stability of all believers. It is said to abide in them, which respects their permanency and establishment in truth against all seducers: nor will anything else be sufficient for this purpose. Temptations may come as a storm, which will quickly drive men from their greatest fleshly confidences. Hence oftentimes those who are forwardest to say, though all men should forsake the truth, yet will not they; are the forwardest upon trials to do so. Neither will men’s skill, or disputing abilities, secure them from being inveigled with fair pretences, or entangled with the cunning sleights of them who lie in wait to deceive. Nor will the best defences of flesh and blood, stand firmly unshaken against powerful allurements on the one hand, and fierce persecution on the other; but this unction the apostle assures believers will not fail, neither shall they fail because of it.”
-From The Holy Spirit His Gifts and Power by John Owen (1616-1683) Published by Kregel Publications Grand Rapids, MI 1954 Pages 341-343.