He names Peter alone because he has received the primacy in the founding of the church; and he himself had likewise been chosen to have the primacy in the founding of Gentile churches, but with the proviso that Peter should preach to the Gentiles, should cause arise, and Paul to the Jews.
Some hold his meaning to be, not only that the Apostles did not instruct him, but that they were instructed by him. But I would not say this, for what could they, each of whom was himself perfectly instructed, have learned from him? He does not therefore intend this by the expression, "contrariwise," but that so far were they from blaming, that they praised him: for praise is the contrary of blame. Some would probably here reply: Why did not the Apostles, if they praised your procedure, as the proper consequence abolish circumcision? Now to assert that they did abolish it Paul considered much too bold, and inconsistent with his own admission. On the other hand, to admit that they had sanctioned circumcision, would necessarily expose him to another objection. For it would be said, if the Apostles praised your preaching, yet sanctioned circumcision, they were inconsistent with themselves. What then is the solution? Is he to say that they acted thus out of condescension to Judaism? To say this would have shaken the very foundation of the economy. Wherefore he leaves the subject in suspense and uncertainty, by the words, "but of those who were reputed to be somewhat; it makes no matter to me." Which is in effect to say, I accuse not, nor traduce those holy men; they know what it is they have done; to God must they render their account. What I am desirous to prove is, that they neither reversed nor corrected my procedure, nor added to it as in their opinion defective, but gave it their approbation and assent; and to this Titus and Barnabas bear witness. Then he adds,
Ver. 7. "When they saw that I had been entrusted with the Gospel of the Uncircumcision even as Peter with the Gospel of the Circumcision ,"—
The Circumcision and Uncircumcision; meaning, not the things themselves, but the nations known by these distinctions; wherefore he adds,
This intricate passage, full of intervening matter, might be briefly construed as follows: “Those who were conspicuous added nothing to me, but on the contrary gave the right hand of fellowship to me and Barnabas.” An alternative sense is hidden to avoid boasting of himself: “Those who were conspicuous added nothing to me, but on the contrary I have added to them, and they have become more steadfast in the grace of the gospel.”
(Vers. 7, 8.) But on the contrary, when they saw that I had been entrusted with the gospel for the uncircumcised, just as Peter had been entrusted with the gospel for the circumcised (for he who worked through Peter for his apostolic ministry to the circumcised worked also through me for mine to the Gentiles), and when James and Cephas and John, who seemed to be pillars, perceived the grace that was given to me, they gave the right hand of fellowship to Barnabas and me, that we should go to the Gentiles and they to the circumcised. Ὑπέρβατον est, et multis quae in medio sunt interjecta sublatis, sic breviter legi potest: Mihi enim qui videbantur esse nihil contulerunt: sed econtra dexteras dederunt mihi et Barnabae, societatis. Aut certe ille absque jactatione sui, occultus est sensus: Mihi qui videbantur esse aliquid, nihil contulerunt; sed econtra a me eis collatum est, dum fiunt in Evangelii gratia firmiores. Totum autem quod dicit, hoc est: unus atque idem mihi Evangelium praeputii, et Petro circumcisionis credidit. He sent me to the Gentiles, and he appointed him in Judea. Neither could the Gentiles, who were no longer young and could not benefit from the pain of circumcision, abstain from the foods they had always been accustomed to and that God had created for them to use; nor could those who believed and were circumcised from the Jews, and who, by custom, thought they had more than the other Gentiles, easily despise the things in which they boasted. Therefore, by the providence of God, one apostle was given to the circumcised, who seemed to acquiesce to the shadows of the Law, while another was given to those who were uncircumcised, who did not consider the grace of the Gospel to be slavery, but rather free faith. Lest any impediment to faith arise under any occasion: and because of circumcision or uncircumcision, one would not believe in Christ. And we do not say this because Peter, who himself also testified that no man is common in the Acts of the Apostles (Acts 10), and is taught in that vessel, which he saw sent from heaven with four corners, that it makes no difference whether someone is a Jew or a Gentile, as if he had forgotten the things that came before, concerning the grace of the Gospel, he considered the Law to be observed. But rather, in order to also pretend to keep the Law himself, gradually leading the Jews away from their ancient way of life. For they could not suddenly and contemptuously cast aside so much labor of observance, and the most careful conduct of their former life, as if it were mere refuse and loss. Hence we may clearly understand why Paul and Barnabas, who were in society with Peter, James, and John, received the right hand of fellowship from them. It was not to prevent the gospel of Christ being thought different among those who hitherto observed various rites, or who held diverse opinions, but to establish a common bond both between those who were circumcised and those who were not. Paul wisely maintained this, when he said, 'For He that wrought effectually in Peter to the apostleship of the circumcision, the same was mighty in me toward the Gentiles; and recognizing the favor conferred upon Peter, he thus explains it, that it might be understood how, in receiving circumcision, he did it in part, in order that he might profit those who had believed in him among the Jews, and keep them in the faith and gospel of Christ.' He also understands that if that person were to act without fault and observe the time when it is not allowed, so as not to lose those entrusted to him, he would have to do more for the truth of the Gospel, namely, what was entrusted to him in secret, so that the nations, discouraged by the burden and difficulty of the Law, would not turn away from the faith and belief in Christ. A hidden question arises here: So what? If Peter were to find [people] from the Gentiles, would he not lead them to the faith? But if Paul had found any from the circumcision, did he not invite them to the baptism of Christ? This is resolved in the following way: that we say that it was commanded for each group, the Jews and the Gentiles, that those who defended the Law would have someone to follow, and those who preferred grace over the Law would have a teacher and guide. But in general, their purpose was to gather the Church of Christ from all the nations. For we read that the Gentile Cornelius was baptized by the holy Peter, and that Paul often preached Christ in the synagogues of the Jews. Peter, John, and James, who seemed to be pillars (Acts X, XIII, XVII). Three times before we have read about the Apostles, but after them were the others who seemed to be something. They made no difference to me, those who seemed important. So I was anxious to know what this meant, those who seemed important, but now he has relieved me of all doubts by adding, who seemed to be pillars. Therefore, the pillars of the Church are the apostles, especially Peter, James, and John, among whom two of them deserve to ascend the mountain with the Lord, one of whom introduces the Savior speaking in the Apocalypse: 'To him who overcomes, I will make him a pillar in the temple of my God' (Rev. 3:12), teaching all believing ones who overcome the adversary that they can become pillars of the Church. Writing to Timothy, Paul says: 'So that you may know how one ought to behave in the household of God, which is the Church of the living God, the pillar and support of the truth' (1 Tim. 3:15). And we are instructed by him and the other apostles, all the believers, and even the Church itself is also called the pillar in the Scriptures. And there is no difference whether it is said about the body or the members, since the body is divided into members and the members are the body. Therefore, Peter, James, and John, who seemed to be pillars, gave the right hand of fellowship to Paul and Barnabas; but Titus, who was with them, did not receive the right hand. For he had not yet reached such a measure, that the merchandises of Christ could be believed to him in equal measure with the elders, and hold the same place of negotiation that Barnabas held, and Paul.
The apostles were not therefore found to disagree in anything. Otherwise, when Paul claimed to have received the gospel perfectly, they might have denied this and wished to add to his teaching, as though he were incomplete. On the contrary, instead of reproving Paul’s imperfection, they approved his perfection.… His saying “on the contrary” might also be understood in such a way as to yield the following meaning: “Upon me those who had a reputation imposed nothing further. On the contrary, they consented with me and Barnabas, joining the right hand of fellowship, that we, for our part, should go among the Gentiles, who are contrary to the circumcision, while they for their part should go to those of the circumcision.”
The sentence beginning with “But on the contrary, seeing ... etc.,” is summed up by the sentence “They extended to me and Barnabas the right hand of fellowship.” Actually he says what he says in between in order to indicate once again that he was not ordained by men to preach to the nations, as his enemies said concerning him
[AD 384] Ambrosiaster on Galatians 2:7