The Apostle John told his readers that they had been anointed with the Holy Spirit.

But you have an anointing from the Holy One, and you know all things...But the anointing which you have received from Him abides in you, and you do not need that anyone teach you; but as the same anointing teaches you concerning all things, and is true, and is not a lie, and just as it has taught you, you will abide in Him (1Jo 2:20, 27).

The only other reference in the New Testament to the anointing of the Spirit was by the Apostle Paul.

Now He who establishes us with you in Christ and has anointed us is God (2Cr 1:21).

From these verses we conclude that it is God who anoints the believer with the Spirit. This "anointing" remains forever with the believer. The purpose of this anointing is that the believer might be taught.