Galatians 2:4

"And that because of the false brethren, privily brought in." Here arises a very important question, Who were these false brethren? If the Apostles permitted circumcision at Jerusalem, why are those who enjoined it, in accordance with the Apostolic sentence, to be called false brethren? First; because there is a difference between commanding an act to be done, and allowing it after it is done. He who enjoins an act, does it with zeal as necessary, and of primary importance; but he who, without himself commanding it, alloweth another to do it who wishes yields not from a sense of its being necessary but in order to subserve some purpose. We have a similar instance, in Paul's Epistle to the Corinthians, in his command to husbands and wives to come together again. To which, that he might not be thought to be legislating for them, he subjoins, "But this I say by way of permission, not of commandment." (1 Cor. vii: 5.) For this was not a judgment authoritatively given but an indulgence to their incontinence; as he says, "for your incontinency." Would you know Paul's sentence in this matter? hear his words, "I would that all men were even as I myself," (1 Cor. vii: 7.) in continence. And so here, the Apostles made this concession, not as vindicating the law, but as condescending to the infirmities of Judaism. Had they been vindicating the law, they would not have preached to the Jews in one way, and to the Gentiles in another. Had the observance been necessary for unbelievers, then indeed it would plainly have likewise been necessary for all the faithful. But by their decision not to harass the Gentiles on this point, they showed that they permitted it by way of condescension to the Jews. Whereas the purpose of the false brethren was to cast them out of grace, and reduce them under the yoke of slavery again. This is the first difference, and a very wide one. The second is, that the Apostles so acted in Judaea, where the Law was in force, but the false brethren, every where, for all the Galatians were influenced by them. Whence it appears that their intention was, not to build up, but entirely to pull down the Gospel, and that the thing was permitted by the Apostles on one ground and zealously practiced by the false brethren on another. "Who came in privily to spy out our liberty, which we have in Christ Jesus, that they might bring us into bondage." He points out their hostility by calling them spies; for the sole object of a spy is to obtain for himself facilities of devastation and destruction, by becoming acquainted with his adversary's position. And this is what those did, who wished to bring the disciples back to their old servitude. Hence too appears how very contrary their purpose was to that of the Apostles; the latter made concessions that they might gradually extricate them from their servitude, but the former plotted to subject them to one more severe. Therefore they looked round and observed accurately and made themselves busybodies to find out who were uncircumcised; as Paul says, "they came in privily to spy out our liberty," thus pointing out their machinations not only by the term "spies," but by this expression of a furtive entrance and creeping in.