For such are false apostles - They have no claim to the apostolic office. They are deceivers. They pretend to be apostles; but they have no divine commission from the Redeemer. Paul had thus far argued the case without giving them an explicit designation as deceivers. But here he says that people who had conducted thus; who attempted to impose on the people; who had brought another gospel, whatever pretences they might have - and he was not disposed to deny that there was much that was plausible - were really impostors and the enemies of Christ. It is morally certain, from 2 Corinthians 11:22, that these people were Jews; but why they had engaged in the work of preaching, or why they had gone to Corinth, cannot with certainty be determined.
Deceitful workers - Impostors. People who practice various arts to impose on others. They were crafty, and fraudulent, and hypocritical. It is probable that they were people who saw that great advantage might be taken of the new religion; people who saw the power which it had over the people, and who saw the confidence which the new converts were inclined to repose in their teachers; perhaps people who had seen the disciples to the Christian faith commit all their property to the hands of the apostles, or who had heard of their doing it (compare Acts 4:34-35), and who supposed that by pretending to be apostles also they might come in for a share of this confidence, and avail themselves of this disposition to commit their property to their spiritual guides. To succeed, it was needful as far as possible to undermine the influence of the true apostles, and take their place in the confidence of the people. Thence they were “deceitful (δόλιοι dolioi) workers,” full of trick, and cunning, and of plausible arts to impose on others.
Transforming themselves ... - Pretending to be apostles. Hypocritical and deceitful, they yet pretended to have been sent by Christ. This is a direct charge of hypocrisy. They knew they were deceivers; and yet they assumed the high claims of apostles of the Son of God.