2 John 1:9

Whosoever goeth onward and abideth not in the teaching of Christ, hath not God: he that abideth in the teaching, the same hath both the Father and the Son.

Whosoever goeth onward and abideth not in the teaching of Christ ... The false teachers evidently considered themselves "advanced thinkers," progressing beyond the teaching of Christ; but the apostle here denied the pretensions of such men. Whoever advances beyond the New Testament, has advanced right out of Christianity. "Our aim should be not to be advanced, but to abide in the doctrine of Christ."[16]

Many have rationalized their departure from the teachings of Jesus Christ through the vain belief that, "Theology is to God's revelation in Grace as science is to his revelation in Nature";[17] but it is not true that the apostles were limited in what they revealed to mankind in the New Testament. The Holy Spirit guided them into "all truth," a fact that was much in John's mind as he wrote these letters; and those theologians who fancy that they are able to discover more and more glorious things concerning God and the redemption of human souls, than those eternal truths revealed in the New Testament, are totally and radically wrong, that being the categorical affirmation of this 2 John 1:1:9.

As MacKnight expressed it:

The person who either neglects to teach any part of the doctrine of Christ, or who teaches what is not the doctrine of Christ, is culpable, and does not acknowledge God.[18]

The heresy of this age is that religious teachers may "go beyond" Christ's teachings in any direction they please, or that they may eliminate from their doctrine any of the Lord's teachings that they hold to be unnecessary or distasteful to themselves. The apostle John, in this verse, sufficiently warned all people that such departures or omissions remove people from any claim of having God.

In a practical sense, of course, this limits authority in the Christian religion to the teachings of the New Testament, because there and there alone may be found the authentic truth "first spoken by the Lord," and delivered unto us "by them that heard him." A proper appreciation of this truth would relegate a great deal of present day religiosity to the ash heap.

[16] Leon Morris, The New Bible Commentary, Revised (Grand Rapids, Michigan: Wm. B. Eerdmans Publishing Company, 1970), p. 1272.

[17] David Smith, op. cit., p. 202.

[18] James Macknight, op. cit., p. 144.