Hereby By the following plain mark; know ye the Spirit of God In a teacher. Every spirit Of a teacher; that confesseth that Jesus Christ is come in the flesh, is of God Doddridge, with many other commentators, reads this clause, Every spirit that confesseth Jesus Christ, who is come in the flesh, is of God: that is, that confesseth him to be the Messiah, the Son of God, the Saviour of the world, and that both with heart and voice, sincerely believing him to be such, and behaving to him and confessing him as such, though this might expose them to the loss of all things, even of their property, liberty, and lives. This must be acknowledged to be a perfectly Scriptural and very proper mark of trial, proving those in whom it was found to be possessed of the Spirit of God and of Christ. Nevertheless, it must be acknowledged, though the original words, ο ομολογει Ιησουν Χριστον εν σαρκι εληλυθοτα, might bear this rendering, they much more favour the sense given them in our translation, signifying, literally and exactly, that confesseth Jesus Christ hath come in the flesh. This imports two things: 1st, That Jesus is the Christ, whose coming was foretold by the Jewish prophets, in opposition to the unbelieving Jews; a truth which those who confessed, whether in Judea or in the Gentile countries, exposed themselves to the danger of having their goods spoiled, and their bodies imprisoned, if not also tortured and put to death. So that those who voluntarily made this confession, manifested that they preferred Christ and his gospel to all other things whatever. The clause imports, 2d, That this great personage, the Messiah, the Son of God, had really come in the flesh, and had a real human nature, in opposition to a sect which arose very early in the Christian Church, called the Docetæ, who would not allow that Christ had a real body, and that he really suffered, died, and rose again. This sect St. John seems to have had in his eye throughout this epistle. Hence, in the very beginning of it, he speaks of seeing, hearing, and handling Christ; and here, to the fundamental article of Jesus's being the Messiah, he adds, that he came in the flesh; with which doctrine his atoning for sin by the sacrifice of himself, and his rising from the dead, the first-fruits of them that sleep, were closely and necessarily connected, and therefore the acknowledgment of it was a point of the greatest importance.
The Socinians indeed contend, that to confess Jesus Christ hath come in the flesh, means simply to confess that he was a mere man: and from this they infer that he had no existence before he was conceived of his mother. In proof of their sense of the clause, they cite Hebrews 2:14, where the writer says he partook of our flesh and blood. Now, though it may be true that these words import nothing more than that Christ was a man, like other men, St. John's words, hath come in the flesh, have evidently a more extensive meaning. For, as Bishop Horsley observes, the sense of a proposition ariseth, not from the meaning of a single word contained in it, but from the union of the whole into one sentence, especially if that union suggests any circumstance by which the sense of the proposition is modified. This is the case of the clause, hath come in the flesh; words which, while they specify the manner of his coming, imply that he might have come in a different manner if he had pleased. Accordingly the apostle hath used the verb to come in that sense 1 John 5:6. This is he who came by water and blood, even Jesus Christ; not by water only, but by the water and the blood. For his meaning plainly is, that Jesus came attested as the Christ by water and blood jointly, although he might have come attested by either of these separately; and that Jesus existed as the Christ before he came attested by the water and the blood. Thus the clause, hath come in the flesh, implies that he might have come in another manner than in the flesh, namely, in the form of God, as mentioned Philippians 2:6-7. It implies that he existed before he came in the flesh, and chose to come in that manner, rather than in any other; consequently that he is more than a mere man. That Jesus Christ might have come in another manner, was the opinion of Clemens Romanus, one of the apostolical fathers mentioned Philippians 4:3: for in his epistle to the Corinthians, he saith, “The sceptre of the majesty of God, our Lord Jesus Christ, came not in the pride of pomp and arrogance, although he had it in his power; but in humility, as the Holy Spirit spake concerning him.” See Macknight, and Bishop Horsley's 5th letter to Priestley.