Blessed Theodoret understands them as those who "seek human glory and provide for their own safety, so that they may not suffer mockery and imprisonment like us who preach Christ." This thought follows directly from the proper interpretation of the expressions used by the Apostle.
The words "to boast according to the flesh" in Greek are ευπροσωπησαι εν σαρκι. Strictly, they mean to present a fair appearance, to be of a fair face in the flesh, fleshly, in appearance, in external life and position. Those who have a fair appearance in this respect are of two kinds. Some are in the religious sphere, and others in everyday life.
In the religious sphere these are fleshly Jews. A man is circumcised, observes Sabbaths and feasts, offers sacrifices, performs washings, gives tithes, and carries out all the other rites. He appears very respectable, and everyone praises him as perfectly pious. Although the false teachers who deceived the Galatians can be assigned to this class of people, one cannot suppose that Saint Paul had this side of them in mind in these words.
From this side it follows well that they urged circumcision, which occupies the first place in their outward religious respectability. But it is not clear how fear of persecutions fits with this. Fear of persecutions presupposes a desire to preserve one's outward condition undisturbed, so that everything there may flow peacefully and calmly.
When someone is persecuted, his property is taken, he is beaten, and he is driven out of house and village. The fair appearance of such a person's outward life is completely destroyed. Therefore one who values outward rest and the favorable course of outward life may rightly be called someone who wants to appear respectable according to the flesh.
This is the very side that Saint Paul brings to view in the false teachers. He says they have one desire: to live peacefully. That is why they preach circumcision. For rejecting circumcision one must suffer persecution, which they fear. If there were no trouble from not insisting on circumcision, they would at once abandon it. More than that, put circumcision in the place of the Cross. Let them be persecuted not for the Cross but for circumcision, and they will at once pass over to the side of the Cross and abandon circumcision.
They have no love for truth. They are wherever it is peaceful. The truth of truth itself is a secondary matter for them, a means and not an end. This quality of theirs is closely connected with man-pleasing, and man-pleasing with vainglory. Saint Paul indicated all this together in the false teachers by calling them those who desire to appear respectable according to the flesh.
Saint Chrysostom says: "The Apostle said this to show that the false teachers did this not for God. It is as though he said: this does not come from piety, but everything is done from human love of honor alone, to please unbelievers. Through the circumcision of the faithful they would rather offend God, if only they may please men."
"These compel you to be circumcised." They compel and force. Clearly, besides persuasion, they used some coercive and oppressive measures, by which the Galatians were placed as though under necessity to accept circumcision. What these were is unknown. But such speech from the Apostle could be addressed to them with the same purpose of persuasion: to make them leave the false teachers more quickly.
For "by showing that they did not fall into this error by themselves but by compulsion, he thereby compels them to leave it. By almost justifying them, he persuades them more quickly to leave the false teachers" (Saint Chrysostom).
"Only that they may not be persecuted for the Cross of Christ." The false teachers in question believed in the Lord. Only, along with faith in Him, they considered it necessary to be circumcised and to keep the whole Law of Moses. Among those who believed in this way, some believed privately and lived quietly, not entering the rank of active workers. Others were not content with this, but undertook to teach others to believe as they did.
Of these, some acted from sincere conviction in the indispensability of the Mosaic Law. Others held to it and persuaded others to do the same only so as not to arm their kinsmen against themselves and undergo persecutions. Saint Paul probably met many such people in Antioch, Jerusalem, and other places. Such people surely slipped in among the Galatians as well. Saint Paul presents them in their true light.
Saint Chrysostom says: "Since the false teachers themselves suffered reproach from the Jews for abandoning the customs of the fathers, they wanted to pervert you to avoid this reproach. They wished to justify themselves before them by your flesh."
Everything in them is cunning and deceit. Nothing is sincere. Blessed Jerome also found a particular point by which they could easily catch the believers, always with the lure of a calm and safe life. "Julius Caesar, Octavian Augustus, and Tiberius, the successor of Augustus, published laws that the Jews scattered throughout the whole Roman Empire should live according to their customs and serve their God as they had received from their fathers. Therefore, whoever was circumcised, even if he believed in Christ, was regarded by the Gentiles as a Jew and was not troubled. But whoever did not accept circumcision and also kept away from paganism was subjected to persecutions both by Gentiles and by Jews. Therefore the corrupters of the Galatians, wishing to avert such persecutions, persuaded the disciples to accept circumcision as a protection for themselves. The Apostle called this confidence in the flesh. For then neither would the Jews persecute them, nor could the Gentiles do anything to them, since proselytes were everywhere. In some places they too were circumcised."