1:7-11 The deceiver and his deceit are described: he brings some error concerning the person or office of the Lord Jesus. Such a one is a deceiver and an antichrist; he deludes souls, and undermines the glory and kingdom of the Lord Christ. Let us not think it strange, that there are deceivers and opposers of the Lord Christ's name and dignity now, for there were such, even in the apostles' times. The more deceivers and deceits abound, the more watchful the disciples must be. Sad it is, that splendid attainments in the school of Christ, should ever be lost. The way to gain the full reward is, to abide true to Christ, and constant in religion to the end. Firm cleaving to Christian truth unites us to Christ, and thereby to the Father also; for they are one. Let us equally disregard such as abide not in the doctrine of Christ, and those who transgress his commands. Any who did not profess and preach the doctrine of Christ, respecting him as the Son of God, and salvation by him from guilt and sin, were not to be noticed and countenanced. Yet in obeying this command, we must show kindness and a good spirit to those who differ from us in lesser matters, but hold firmly the all-important doctrines of Christ's person, atonement, and holy salvation.
10. If there come any—as a teacher or brother. The Greek is indicative, not subjunctive; implying that such persons do actually come, and are sure to come; when any comes, as there will. True love is combined with hearty renunciation and separation from all that is false, whether persons or doctrines.
receive him not … neither bid him God speed—This is not said of those who were always aliens from the Church, but of those who wish to be esteemed brethren, and subvert the true doctrine [Grotius]. The greeting salutation forbidden in the case of such a one is that usual among Christian brethren in those days, not a mere formality, but a token of Christian brotherhood.