After the second didache [English: "teaching" or "doctrine"] the Textus Receptus [and the KJV], following K L P most miniscules cop(bo) eth, adds tou Christou [English: "of Christ"]. This reading is obviously secondary, the result of scribal assimilation to the first part of the sentence.

Verse 9 indicates the significance of right confession in two sentences standing in antithetical parallelism, in obvious imitation of 1 Jn 2:23f. The negative side is given first... He who follows the heretical doctrine is characterized as one who goes too far, and thus as one who goes beyond legitimate teaching, as me menon ("who does not abide") indicates. This could of course be said of those who, as Gnostics or gnosticizing Christians, strive for higher knowledge or think they have attained it. It is not said of a "deceiver" as such, but of all those who permit themselves to be deceived, as the pas ("any one") inidcates (as in 1Jn 2:23 also). From the standpoint of the person, menein ("abides") means faithfulness. That faithfulness consists in abiding in the didache to Christou ("doctrine of Christ") represents a distinction from 1 John, where the concept of didache is not met. But it is found in Jn 7:16f; 18:19 With these passages in mind, tou Chrisou ("of Christ") may be taken as a subjective genetive; it is more probable, however, that "of Christ" is an objective genitive, since the author hangs everything on his christology, i.e., on the doctrine about Christ, as v 7 shows. Judgment is passed on the disciples of the heretical doctrine... That means: he stands outside the fellowship of God.

The positive side of the antithesis ... corresponds to 1Jn 2:24, from which the concept of menein ("abides"), i.e., faithfulness, is derived....

"The doctrine of Christ", preferably, "the teaching of Christ". This may mean "what Christ teaches", or what is taught about Christ. The former is preferable here, cp. Jn. 7:16f. The reference is to what Christ told his followers about the will of God and the true way of life.

The teaching of Christ is ambiguous. It may mean the doctrine concerning him, and so be equivalent in sense to the passage in 1J; but it may refer to Jesus' teaching, specifically no doubt , the command to love... As we have seen, failure to hold doctrinal or moral orthodoxy is equally pernicious in the eyes of our writer, equally dire in its effects.