John Gill

This persuasion cometh not of him that calleth you. That is, the opinion they were persuaded to believe; and which the Syriac version renders, "your persuasion"; this is not of God, who had called them into the grace of Christ; nor of Christ, who had called them to the knowledge of himself, and communion with him; nor of the Spirit of Christ, who had called them with an holy calling, and who still continued to call them to repentance; nor of any faithful minister of the Gospel, who had been concerned as an instrument in their effectual calling; meaning the notion they were persuaded to give into, that circumcision and the works of the law were necessary to salvation, and that these were to be joined with the righteousness of Christ for justification; such a conceit as this could never be of God, nor any evangelical minister, but must be of Satan or his emissaries, the false apostles. This persuasion cometh not of him that calleth you. That is, the opinion they were persuaded to believe; and which the Syriac version renders, "your persuasion"; this is not of God, who had called them into the grace of Christ; nor of Christ, who had called them to the knowledge of himself, and communion with him; nor of the Spirit of Christ, who had called them with an holy calling, and who still continued to call them to repentance; nor of any faithful minister of the Gospel, who had been concerned as an instrument in their effectual calling; meaning the notion they were persuaded to give into, that circumcision and the works of the law were necessary to salvation, and that these were to be joined with the righteousness of Christ for justification; such a conceit as this could never be of God, nor any evangelical minister, but must be of Satan or his emissaries, the false apostles. Galatians 5:9 gal 5:9 gal 5:9 gal 5:9A little leaven leaveneth the whole lump. A proverbial expression pretty much in use with the Jews; see Co1 5:6, respecting either persons or things; and is in answer to, or prevents an objection that might be made, or something that might be said, in favour of these churches; that their case was not so bad, or the danger they were in so great, as was represented by the apostle; since they were only a few persons that propagated this notion, and but few that received it, at least thoroughly gave into it; and that, if it was an error, it was but a small one, and only regarded a single ritual, or a few rituals of the law; to which the apostle replies, by supposing, but not granting this to be the case, since they were pretty generally declined, and the error was not a slight one, that as a little sour leaven influences and ferments a large mass, or lump of dough, and makes it of the same nature with it, so a small error in doctrine, as it may be thought to be, increases to more ungodliness, and eats as doth a canker; and though a few hands may be first concerned in propagating it, and but few be infected with it, yet these may soon spread the contagion through the whole society: wherefore errors and false teachers should be nipped in the bud, and stopped in their beginnings, how inconsiderable soever they and their tenets may be judged to be.