John Chrysostom — on Gal 1:1 (Homily on Galatians 1)

“Since Paul then saw the whole Galatian people in a state of excitement, a flame kindled against their Church, and the edifice shaken and tottering to its fall, filled with the mixed feelings of just anger and despondency, he writes the Epistle as an answer to these charges. This is his aim from the very commencement, for the underminers of his reputation had said, The others were disciples of Christ but this man of the Apostles. Wherefore he begins thus, "Paul, an Apostle not from men, neither through man." For, these deceivers, as I was saying before, had said that this man was the last of all the Apostles and was taught by them, for Peter, James, and John, were both first called, and held a primacy among the disciples, and had also received their doctrines from Christ Himself; and that it was therefore fitting to obey them rather than this man; and that they forbad not circumcision nor the observance of the Law. By this and similar language and by depreciating Paul, and exalting the honor of the other Apostles, though not spoken for the sake of praising them, but of deceiving the Galatians, they induced them to adhere unseasonably to the Law. Hence the propriety of his commencement.”