The so-called "painful letter," which is found in Chapters 10–13 of 2 Corinthians, contains Paul's defense of himself and of his work to the charges made against him by his enemies, including the Jewish legalists who said that Paul was an impostor who had not been authorized by the proper authorities to work among the churches. The legalists supported their charge by pointing out that Paul had a "thorn in [his] flesh," some physical defect that, according to ancient Jewish regulations, would have barred a man from the priesthood. They further maintained that Paul supported himself by doing manual labor rather than by accepting support from the members of the church. This labor, in their judgment, was an admission on his part that he was not qualified to be supported in the way that was customary for duly authorized missionaries. The legalists also accused Paul of cowardice on the grounds that he was bold so long as he was writing letters, but he was very mild when present with the legalists in person. Other charges of a similar nature were made in an all-out attempt to discredit the religious work that Paul was doing.
To all of these charges, Paul makes a vigorous reply. He shows wherein the charges are false, and he recounts for the people at Corinth the many trials and hardships that he suffered for their sake and for the sake of the gospel. Although he apologizes for seeming to boast of his own attainments, he explains the necessity for doing so. He indicates further that his greatest disappointment lies not in the fact that charges of this sort have been made against him but that the members of the Corinthian church have apparently been persuaded by them.
The first nine chapters of what is now called 2 Corinthians are a letter that appears to have been written some time after the "painful letter" was received and accepted by the church. This letter contains an expression of gratitude for the change that has taken place among the Corinthian believers. Paul rejoices that they are now on the right track again, and he summarizes for them the essential meaning of the gospel that he first proclaimed to them. Using the language of the Old Testament prophet Jeremiah, Paul tells them that the Christian gospel is none other than the New Covenant, written "not on tablets of stone but on tablets of human hearts." Toward the close of the letter, he again reminds them of the collection to be taken for the poor in Jerusalem.
