But the anointing that you received from him abides in you, and you have no need that anyone should teach you. But as his anointing teaches you about everything, and is true, and is no lie—just as it has taught you, abide in him.
John is not saying that we no longer need human teachers, but that they do not need anyone to lay again the foundation of basic belief.
John’s point is that believers must not rely on human wisdom or man-centered philosophy, but on the teaching of God’s Word by Spirit-gifted human teachers and the illuminating work of the Holy Spirit.