John contrasts false teachers and true teachers in verses 18–21. The presence of false teachers is a sign of the end times (18) and their defection is proof of their true nature (19).
The second mark of false teachers is they deny the faith. In verse 20, John places the pronoun “you” in emphatic position at the beginning of the clause. This creates a strong contrast between the false teachers and John’s readers. False teachers deny the basic truths of Christianity as taught by Jesus and as revealed in the Bible, but true believers have an anointing from the “Holy One.” This designation could refer to Jesus or the Holy Spirit. Since Jesus is the one who promised the Holy Spirit to the disciples in John’s Gospel, there is a sense in which both referents apply here. This is the first indirect reference to the Holy Spirit in the letter. John will refer to the Holy Spirit directly six times in the letter.
In verses 24 and 25, John now draws it all together with a challenge and a promise. The placement of “you” in the emphatic position in the clause in Greek strongly contrasts true believers with the false teachers of the previous verses.
This paragraph contains four constituents: 18-19, 20-21, 22-23, 24-25. The first three provide support for the appeal in vv. 24-25. The sermon outline structure would look something like this:
A. Departure of false teachers confirms their unsaved status – (vv. 18–19).
B. The Holy Spirit confirms your knowledge of the truth – (vv. 20–21).
C. Denial of the Son is denial of the Father as well – (vv. 22–23).
I. Abide in the Father and the Son, which is eternal life – (vv. 24–25).