Chapters 10-13
The last four chapters of the epistle are a defence of Paul’s apostleship. Defending his apostleship was the most difficult and painful part of his communications with the Corinthians, because he would have to speak of himself more directly than he had done in the first section of the epistle—and this was something he didn’t want to do. It also required directly exposing his detractors who were challenging his apostleship—which was another thing that he had no desire to do.
It is very interesting to see the credentials that Paul gives in these chapters to prove that he was truly an apostle of Christ. He does not bring forth a diploma to show that he had graduated from some accredited college. Neither does he present an official letter signed by the apostles in Jerusalem stating that they had ordained him. Instead, he presents the signs of a true apostle and his work. All Christians, since they are ministers of Christ, should have the moral characteristics outlined in chapters 1-7, but they cannot claim to have these apostolic powers and signs that Paul refers to in this section—at least not in the proportions in which he speaks. (Perhaps this is why these things are taken up in a separate section of the epistle.) These signs, of which Paul now speaks, undeniably attest to the fact that he was an apostle indeed.
In the first section of the epistle (chaps. 1-7) Paul was addressing the large majority of the Corinthians whom he regarded as his friends, and was endeavouring to remove the suspicions they may have had as to his integrity and sincerity as a minister of Christ. Trusting that he had gained the confidence of the saints in the foregoing chapters, he now deals with his opposers more directly. Without addressing them by name, he confronts, exposes, and rebukes those who had assailed him and his apostleship; at the same time he lays out a portrait of what a true apostle is.
These false workers were glorying in the flesh, and in order to exalt themselves, they sought to discredit the Apostle by calling in question the apostolic authority given to him by God. They made certain charges against him in an attempt to assault his character and contradict his teaching, and ultimately they assumed a false authority over his converts in Corinth. Thus, it became necessary for Paul to vindicate his apostleship, and at the same time, to inform and warn the Corinthians of these false workers. They needed to see these charlatans for what they really were—being “false apostles” and “deceitful workers” who were doing Satan’s work among the saints (chap. 11:13-15).
Paul waited to address this matter last, hoping that the foregoing chapters would have established the Corinthians' confidence in him, and hence, accept what he was about to say in this exposure. Since this was an open letter to the assembly, he could not be accused of saying these things behind his critics’ backs, as was the case with his detractors.