The Greek crisma (chrisma) figuratively denotes the special endowment (“chrism”) of the Holy Spirit—His anointing or unction.
But you have an anointing from the Holy One, and you all have knowledge (1 John 2:20).
The anointing you received from Him remains in you, and you don’t need anyone to teach you. Instead, His anointing teaches you about all things, and is true and is not a lie; just as it has taught you, remain in Him (1 John 2:27).
From the whole tenor of this letter, it is obvious that the apostle is guarding the Christians against seducers and deceivers, who were disturbing and striving to corrupt the Church. Thus, the Spirit’s anointing imparts every truth of God necessary for salvation so the believer has no need of that knowledge of which the seducers or Gnostics boast.
It is not enough to learn truth from human teachers; we must listen to the teaching of the Spirit. There are great truths to be spiritually learned (1 Corinthians 2:9-14).