The internal and external evidence for Paul's authorship is conclusive. The style is characteristically Pauline. The superscription, and allusions to the apostle of the Gentiles in the first person, throughout the Epistle, establish the same truth (Ga 1:1, 13-24; 2:1-14). His authorship is also upheld by the unanimous testimony of the ancient Church: compare Irenæus [Against Heresies, 3,7,2] (Ga 3:19); Polycarp [Epistle to the Philippians, 3] quotes Ga 4:26; 6:7; Justin Martyr, or whoever wrote the Discourse to the Greeks, alludes to Ga 4:12; 5:20.
The Epistle was written |TO THE CHURCHES OF Galatia| (Ga 1:2), a district of Asia Minor, bordering on Phrygia, Pontus, Bithynia, Cappadocia, and Paphlagonia. The inhabitants (Gallo-græci, contracted into Galati, another form of the name Celts) were Gauls in origin, the latter having overrun Asia Minor after they had pillaged Delphi, about 280 B.C. and at last permanently settled in the central parts, thence called Gallo-græcia or Galatia. Their character, as shown in this Epistle, is in entire consonance with that ascribed to the Gallic race by all writers. Cæsar [Commentaries on the Gallic War, 4,5], |The infirmity of the Gauls is that they are fickle in their resolves and fond of change, and not to be trusted.| So Thierry (quoted by Alford), |Frank, impetuous, impressible, eminently intelligent, but at the same time extremely changeable, inconstant, fond of show, perpetually quarrelling, the fruit of excessive vanity.| They received Paul at first with all joy and kindness; but soon wavered in their allegiance to the Gospel and to him, and hearkened as eagerly now to Judaizing teachers as they had before to him (Ga 4:14-16). The apostle himself had been the first preacher among them (Ac 16:6; Ga 1:8; 4:13; see on Ga 4:13; |on account of infirmity of flesh I preached unto you at the first|: implying that sickness detained him among them); and had then probably founded churches, which at his subsequent visit he |strengthened| in the faith (Ac 18:23). His first visit was about A.D.51, during his second missionary journey. Josephus [Antiquities, 16.62] testifies that many Jews resided in Ancyra in Galatia. Among these and their brethren, doubtless, as elsewhere, he began his preaching. And though subsequently the majority in the Galatian churches were Gentiles (Ga 4:8, 9), yet these were soon infected by Judaizing teachers, and almost suffered themselves to be persuaded to undergo circumcision (Ga 1:6; 3:1, 3; 5:2, 3; 6:12, 13). Accustomed as the Galatians had been, when heathen, to the mystic worship of Cybele (prevalent in the neighboring region of Phrygia), and the theosophistic doctrines connected with that worship, they were the more readily led to believe that the full privileges of Christianity could only be attained through an elaborate system of ceremonial symbolism (Ga 4:9-11; 5:7-12). They even gave ear to the insinuation that Paul himself observed the law among the Jews, though he persuaded the Gentiles to renounce it, and that his motive was to keep his converts in a subordinate state, excluded from the full privileges of Christianity, which were enjoyed by the circumcised alone (Ga 5:11, Ga 4:16, compare with Ga 2:17); and that in |becoming all things to all men,| he was an interested flatterer (Ga 1:10), aiming at forming a party for himself: moreover, that he falsely represented himself as an apostle divinely commissioned by Christ, whereas he was but a messenger sent by the Twelve and the Church at Jerusalem, and that his teaching was now at variance with that of Peter and James, |pillars| of the Church, and therefore ought not to be accepted.
His PURPOSE, then, in writing this Epistle was: (1) to defend his apostolic authority (Ga 1:11-19; 2:1-14); (2) to counteract the evil influence of the Judaizers in Galatia (Ga 3:1-4:31), and to show that their doctrine destroyed the very essence of Christianity, by lowering its spirituality to an outward ceremonial system; (3) to give exhortation for the strengthening of Galatian believers in faith towards Christ, and in the fruits of the Spirit (Ga 5:1-6:18). He had already, face to face, testified against the Judaizing teachers (Ga 1:9; 4:16; Ac 18:23); and now that he has heard of the continued and increasing prevalence of the evil, he writes with his own hand (Ga 6:11: a labor which he usually delegated to an amanuensis) this Epistle to oppose it. The sketch he gives in it of his apostolic career confirms and expands the account in Acts and shows his independence of human authority, however exalted. His protest against Peter in Ga 2:14-21, disproves the figment, not merely of papal, but even of that apostle's supremacy; and shows that Peter, save when specially inspired, was fallible like other men.
There is much in common between this Epistle and that to the Romans on the subject of justification by faith only, and not by the law. But the Epistle to the Romans handles the subject in a didactic and logical mode, without any special reference; this Epistle, in a controversial manner, and with special reference to the Judaizers in Galatia.
The STYLE combines the two extremes, sternness. (Ga 1:1-24; 3:1-5) and tenderness (Ga 4:19, 20), the characteristics of a man of strong emotions, and both alike well suited for acting on an impressible people such as the Galatians were. The beginning is abrupt, as was suited to the urgency of the question and the greatness of the danger. A tone of sadness, too, is apparent, such as might be expected in the letter of a warm-hearted teacher who had just learned that those whom he loved were forsaking his teachings for those of perverters of the truth, as well as giving ear to calumnies against himself.
The TIME OF WRITING was after the visit to Jerusalem recorded in Ac 15:1, &c.; that is, A.D.50, if that visit be, as seems probable, identical with that in Ga 2:1. Further, as Ga 1:9 (|as we said before|), and Ga 4:16 (|Have [Alford] I become your enemy?| namely, at my second visit, whereas I was welcomed by you at my first visit), refer to his second visit (Ac 18:23), this Epistle must have been written after the date of that visit (the autumn of A.D.54). Ga 4:13, |Ye know how ... I preached ... at the first| (Greek, |at the former time|), implies that Paul, at the time of writing, had been twice in Galatia; and Ga 1:6, |I marvel that ye are so soon removed,| implies that he wrote not long after having left Galatia for the second time; probably in the early part of his residence at Ephesus (Ac 18:23; 19:1, &c., from A.D.54, the autumn, to A.D.57, Pentecost) [Alford]. Conybeare and Howson, from the similarity between this Epistle and that to the Romans, the same line of argument in both occupying the writer's mind, think it was not written till his stay at Corinth (Ac 20:2, 3), during the winter of 57-58, whence he wrote his Epistle to the Romans; and certainly, in the theory of the earlier writing of it from Ephesus, it does seem unlikely that the two Epistles to the Corinthians, so dissimilar, should intervene between those so similar as the Epistles to the Galatians and Romans; or that the Epistle to the Galatians should intervene between the second to the Thessalonians and the first to the Corinthians. The decision between the two theories rests on the words, |so soon.| If these be not considered inconsistent with little more than three years having elapsed since his second visit to Galatia, the argument, from the similarity to the Epistle to the Romans, seems to me conclusive. This to the Galatians seems written on the urgency of the occasion, tidings having reached him at Corinth from Ephesus of the Judaizing of many of his Galatian converts, in an admonitory and controversial tone, to maintain the great principles of Christian liberty and justification by faith only; that to the Romans is a more deliberate and systematic exposition of the same central truths of theology, subsequently drawn up in writing to a Church with which he was personally unacquainted. See on Ga 1:6, for Birks's view. Paley [Horæ Paulinæ] well remarks how perfectly adapted the conduct of the argument is to the historical circumstances under which the Epistle was written! Thus, that to the Galatians, a Church which Paul had founded, he puts mainly upon authority; that to the Romans, to whom he was not personally known, entirely upon argument.