By Martin Luther
St. Paul wrote this epistle because, after his departure from the Galatian churches, Jewish-Christian fanatics moved in, who perverted Paul's Gospel of man's free justification by faith in Christ Jesus.
The world bears the Gospel a grudge because the Gospel condemns the religious wisdom of the world. Jealous for its own religious views, the world in turn charges the Gospel with being a subversive and licentious doctrine, offensive to God and man, a doctrine to be persecuted as the worst plague on earth.
As a result we have this paradoxical situation: The Gospel supplies the world with the salvation of Jesus Christ, peace of conscience, and every blessing. Just for that the world abhors the Gospel.
These Jewish-Christian fanatics who pushed themselves into the Galatian churches after Paul's departure, boasted that they were the descendants of Abraham, true ministers of Christ, having been trained by the apostles themselves, that they were able to perform miracles.
In every way they sought to undermine the authority of St. Paul. They said to the Galatians: 'You have no right to think highly of Paul. He was the last to turn to Christ. But we have seen Christ. We heard Him preach. Paul came later and is beneath us. It is possible for us to be in error-we who have received the Holy Ghost? Paul stands alone. He has not seen Christ, nor has he had much contact with the other apostles. Indeed, he persecuted the Church of Christ for a long time.'
10When men claiming such credentials come along, they deceive not only the naive, but also those who seemingly are well-established in the faith. This same argument is used by the papacy. 'Do you suppose that God for the sake of a few Lutheran heretics would disown His entire Church? Or do you suppose that God would have left His Church floundering in error all these centuries?' The Galatians were taken in by such arguments with the result that Paul's authority and doctrine were drawn in question.
Against these boasting, false apostles, Paul boldly defends his apostolic authority and ministry. Humble man that he was, he will not now take a back seat. He reminds them of the time when he opposed Peter to his face and reproved the chief of the apostles.
Paul devotes the first two chapters to a defense of his office and his Gospel, affirming that he received it, not from men, but from the Lord Jesus Christ by special revelation, and that if he or an angel from heaven preach any other gospel than the one he had preached, he shall be accursed.