2 John 1:9

“Whosoever transgresseth, etc.] Not the law of God, of which everyone is a transgressors and that daily, in thought, word, or deed; but who passes over the rule and standard of doctrine, the word of God, and will not adhere to that, nor walk according to it, but rejects and despises that rule: and abideth not in the doctrine of Christ; which he received from his Father, and delivered to his apostles, and of which he is the sum and substance; the doctrine which is concerning his person as the Son of God, and as truly God, and the union of the two natures, divine and human, in his one person; and concerning his office, as the Mediator, surety, and messenger of the covenant, and as the prophet,…”

“The loss (Jo2 1:8) meant is here explained: the not having God, which results from abiding not in the doctrine of Christ. transgresseth--The oldest manuscripts and versions read, "Every one who takes the lead"; literally, "goes," or "leads on before"; compare Joh 10:4, "He goeth before them" (not the same Greek). Compare Jo3 1:9, "Loveth to have the pre-eminence." hath not God-- (Jo1 2:23; Jo1 5:15). The second "of Christ" is omitted in the oldest manuscripts, but is understood in the sense. He--emphatical: He and He alone.”

“Whosoever transgresseth, and abideth not in the doctrine of Christ, hath not God - In the doctrine which Christ taught, or the true doctrine respecting him. The language is somewhat ambiguous, like the phrase “the love of Christ,” which may mean either his love to us, or our love to him. Compare John 15:9. It is difficult to determine here which is the true sense - whether it means the doctrine or precepts which he taught, or the true doctrine respecting him. Macknight understands by it the doctrine taught by Christ and his apostles. It would seem most probable that this is the sense of the passage, but then it would include, of course, all that Christ taught respecting himself, as well as…”

“Receive this as a certain rule: Whosoever transgresseth - Any law of God. Hath not God - For his Father and his God. He that abideth in the doctrine of Christ - Believing and obeying it. He hath both the Father and the Son - For his God. 2 John 1:10”

“1:9 Anyone who wanders away from this teaching (literally everyone going beyond and not remaining in the teaching): To go beyond is to contradict the apostolic teachings about Jesus Christ and believe things about Jesus that were not taught by the apostles. This is a warning to the church not to listen to the false teachers.”

“abideth not: Joh 15:6; Jo1 2:22-24 the doctrine: Joh 7:16, Joh 7:17; Act 2:42; Col 3:16; Tit 2:10; Heb 6:1 hath not: Mat 11:27; Luk 10:22; Joh 5:23, Joh 14:6 He that: Heb 3:14 he hath: Jo1 1:3 2 John 1:10”