Our apostle having warned them against the danger of covetousness in the foregoing verses, he cautions them against the danger of deceit in these; he tells them, that this is the last time of the Jewish dispensation, and that the destruction of their city, temple, and polity, was now at hand; and as they had heard that antichrist should come, accordingly now there were many antichrists come; that is, opposers of Christ, and deniers of him to be the Christ; and by the swarming of these seducers and false teachers now, according to our Saviour's prediction, Matthew 24 they might well conclude it was the last time.
Observe next, These antichrists are described by the communion which they once were of, to wit, the Christian communion; They went out from us, from us apostles, and from us Christians, being false brethren, and unsound Christians; for if they had been of us, as members of the same body, and had joined with us apostles, in planting and propagating the same Christian faith, They would no doubt have continued with us, professing the same faith, and preaching the same doctrine which we do; but they left us, that it might be made manifest that they were not all of us.
Here note, That these antichristian impostors had been in the bosom of the church, and made a profession of the Christian faith; so did the false apostles, the judaizing teachers, mentioned Act_25:1; so did Simon Magus, Nicholas, and Cerinthus. The church's seeming members proves her worst friends, the foxes within do more mischief that the wild boar without.
Quest. But is it not then lawful to depart from the communion of a church whereof we have been formerly members?
Ans. Yes, if she departs from herself: if she degenerates and grows so corrupt a body, and be so far infected, that we cannot communicate with her without sin, which was th case between us and the church of Rome, her doctrines were erroneous, her worship idolatrous; we went out from them, because they went out from the ancient apostolical church. Non fugimus; sed fugamur: Not we, but they made the separation, and consequently the schism lies at their door.