As he begins to draw this brief letter to a close, John issues a solemn warning against fraternization with those who do not hold to apostolic doctrine.  John knew nothing of the kind of “Christian unity” that is boasted of today, in which all the different churches and denominations can lay aside their differences and come together to feel good about each other and pat one another on the back.  It was said of the men who constituted an early gathering of the World Council of Churches, that they agreed upon everything because they believed nothing.  John, on the other hand, was certainly for love and forbearance so far as the laws of Christ would permit, but he absolutely insisted upon complete separation from those who departed from the fundamentals of the Gospel.  Such heretics should not, he declares, even be received into one’s house, much less offered a wish for God speed.  “He that biddeth him God speed,” says the apostle, “is partaker of his evil deeds.”  We dare not wish any success to the evangelists of false gospels, but should in fact resist them with every lawful means in our power, and warn others against the perverse doctrine that they are peddling.  A Jehovah’s Witness or Mormon missionary who comes to our door should not be heard for a moment, but should immediately be sent packing with a warning of the peril in which they stand before God, except they come to honor the Son even as they honor the Father.

It might perhaps be asked what doctrine specifically does John refer to in verse 10.  Since John does not plainly mention any particular doctrine, it is probably impossible to answer this question with any precision.  We should do no harm if we give it the broadest interpretation possible, and relate it to all the fundamentals of the faith: the inspiration of scripture, the doctrine of the Trinity, the deity and the incarnation of the Son of God, the propitiatory sacrifice of Christ, His resurrection, and His second coming.  I do think, however, that most likely John is referring to those doctrines which concern the person of Christ.  This was always his strongest emphasis, for the beloved apostle was always very jealous to uphold the glorious dignity of his Lord’s person.  He had warned against heresies pertaining to the person of Christ in verse 7, denouncing those why confess not that Jesus Christ is come in the flesh as deceivers and antichrists.  Moreover, we have just observed in verse 9 how that he plainly taught the deity of Christ, by first using the phrase “hath not God,” then giving the positive side of the coin, “hath both the Father and the Son.”  I think, then, that in verses 10 and 11 he is warning us to have no friendly intercourse whatsoever with those who reject the apostolic doctrine of the person of Christ.  If a person denies that Jesus Christ is the true and proper Son of God, that He is “God manifest in the flesh,” that He was and is God, is the Creator of all things, then we must have no fellowship with him, nor wish him any success in his heretical expeditions.  The purity of the doctrine of Christ must be jealously maintained by the church in every generation.