If there come any unto you - Any professed teacher of religion. There can be no doubt that she to whom this Epistle was written was accustomed to entertain such teachers.
And bring not this doctrine - This doctrine which Christ taught, or the true doctrine respecting him and his religion.
Receive him not into your house - This cannot mean that no acts of kindness, in any circumstances, were to be shown to such persons; but that there was to be nothing done which could be fairly construed as encouraging or countenancing them as "religious teachers." The true rule would seem to be, in regard to such persons, that, so far as we have contact with them as neighbors, or strangers, we are to be honest, true, kind, and just, but we are to do nothing that will countenance them as religious teachers, We are not to aid their instruction, Proverbs 19:27; we are not to receive them into our houses, or to entertain them as religious teachers; we are not to commend them to others, or to give them any reason to use our names or influence in propagating error. It would not be difficult to practice this rule, and yet to show to others all the kindness, and all the attention in circumstances of need, which religion demands. A person who is truly consistent is never suspected of countenancing error, even when he is distinguished for liberality, and is ready, like the good Samaritan, to pour in oil and wine in the wounds of any waylaid traveler. The command not to "receive such an one into the house," in such circumstances as those referred to by John, would be probably understood literally, as he doubtless designed that it should be. To do that, to meet such persons with a friendly greeting, would be construed as countenancing their doctrine, and as commending them to others; and hence it was forbidden that they should be entertained as such. This treatment would not be demanded where no such interpretation could be put on receiving a friend or relative who held different and even erroneous views, or in showing kindness to a stranger who differed from us, but it would apply to the receiving and entertaining "a professed teacher of religion, as such;" and the rule is as applicable now as it was then.
Neither bid him God speed - Καὶ χαίρειν αὐτῷ μὴ λέγετε Kai chairein autō mē legete - "and do not say to him, hail, or joy." Do not wish him joy; do not hail, or salute him. The word used expresses the common form of salutation, as when we wish one health, success, prosperity, Matthew 26:49; Acts 15:23; Acts 23:26; James 1:1. It would be understood as expressing a wish for success in the enterprise in which they were embarked; and, though we should love all people, and desire their welfare, and sincerely seek their happiness, yet we can properly wish no one success in career of sin and error.

If there come any unto you - Under the character of an apostle or evangelist, to preach in your house; and bring not this doctrine, that Jesus is come in the flesh, and has died for the redemption of the world.
Receive him not unto your house - Give him no entertainment as an evangelical teacher. Let him not preach under your roof.
Neither bid him God speed - Και χαιρειν αυτῳ μη λεγερε· And do not say, Health to him - do not salute him with Peace be to thee! The usual salutation among friends and those of the same religion in the east is, Salam aleekum, "Peace be to you;" which those of the same religion will use among themselves, but never to strangers, except in very rare cases. This is the case to the present day; and, from what John says here, it was a very ancient custom. We have often seen that peace among the Hebrews comprehended every spiritual and temporal blessing. The words mean, according to the eastern use of them, "Have no religious connection with him, nor act towards him so as to induce others to believe you acknowledge him as a brother."

(5) If there come any unto you, and bring not this doctrine, receive him not into [your] house, neither bid him God speed:
(5) We should have nothing to do with those who defend perverse doctrine.

If there come any unto you,.... Under the character of a preacher;
and bring not this doctrine; or does not preach the doctrine of Christ, as before explained, but despises it, and preaches a contrary one:
receive him not into your house; neither into the house of God, suffer him not to preach there; nor into your own house, give him no entertainment there: false teachers always tried to creep into houses, where they served their own turn every way, both by feeding their bellies, and spreading their pernicious doctrines; and therefore such should: be avoided, both publicly and privately; their ministry should not be attended on in the church, or house of God; and they should not be entertained in private houses, and much less caressed:
neither bid him God speed; or give him the usual civil form of salutation, as a good day to you, all hail, all health and prosperity attend you, the Lord be with you, and the like. The word used by the Jews was which signifies "happiness"; so it is said (i), what do they salute with? "God speed"; which was forbidden to say to one that was ploughing in the seventh year. The meaning is, that with such no familiar conversation should be had, lest any encouragement should be given them; or it should induce a suspicion in the minds of other saints, that they are in the same sentiments; or it should tend to make others think favourably of them, and be a snare and a stumblingblock to weak Christians.
(i) T. Hieros. Sheviith, fol. 35. 2. Vid. Taanith. fol. 64. 2.

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.

If any came to you - Either as a teacher or a brother. And bring not this doctrine - That is, advance anything contrary to it. Receive him not into your house - As either a teacher or a brother - Neither bid him God speed - Give him no encouragement therein.