4 Now if, knowing as I do your life and conversation, I do not believe in regard to you that you have spoken anything with an intention of dissimulation and deceit, how much more reasonable is it for me to believe, in regard to the Apostle Paul, that he did not think one thing and affirm another when he wrote of Peter and Barnabas: “When I saw that they walked not uprightly, according to the truth of the gospel, I said unto Peter before them all, 'If you, being a Jew, livest after the manner of the Gentiles, and not as to the Jews, why do you compel the Gentiles to live as do the Jews?'” For whom can I confide in, as assuredly not deceiving me by spoken or written statements, if the apostle deceived his own “children,” for whom he “travailed in birth again until Christ (who is the Truth) were formed in them”? After having previously said to them, “The things which I write unto you, behold, before God, I lie not,” could he in writing to these same persons state what was not true, and deceive them by a fraud which was in some way sanctioned by expediency, when he said that he had seen Peter and Barnabas not walking uprightly, according to the truth of the gospel, and that he had withstood Peter to the face because of this, that he was compelling the Gentiles to live after the manner of the Jews?
5. But you will say it is better to believe that the Apostle Paul wrote what was not true, than to believe that the Apostle Peter did what was not right. On this principle, we must say (which far be it from us to say), that it is better to believe that the gospel history is false, than to believe that Christ was denied by Peter; and better to charge the book of Kings [second book of Samuel] with false statements, than believe that so great a prophet, and one so signally chosen by the Lord God as David was, committed adultery in lusting after and taking away the wife of another, and committed such detestable homicide in procuring the death of her husband. Better far that I should read with certainty and persuasion of its truth the Holy Scripture, placed on the highest (even the heavenly) pinnacle of authority, and should, without questioning the trustworthiness of its statements, learn from it that men have been either commended, or corrected, or condemned, than that, through fear of believing that by men, who, though of most praiseworthy excellence, were no more than men, actions deserving rebuke might sometimes be done, I should admit suspicions affecting the trustworthiness of the whole “oracles of God.”
6. The Manichæans maintain that the greater part of the Divine Scripture, by which their wicked error is in the most explicit terms confuted, is not worthy of credit, because they cannot pervert its language so as to support their opinions; yet they lay the blame of the alleged mistake not upon the apostles who originally wrote the words, but upon some unknown corrupters of the manuscripts. Forasmuch, however, as they have never succeeded in proving this by more numerous and by earlier manuscripts, or by appealing to the original language from which the Latin translations have been drawn, they retire from the arena of debate, vanquished and confounded by truth which is well known to all. Does not your holy prudence discern how great scope is given to their malice against the truth, if we say not (as they do) that the apostolic writings have been tampered with by others, but that the apostles themselves wrote what they knew to be untrue?
7. You say that it is incredible that Paul should have rebuked in Peter that which Paul himself had done. I am not at present inquiring about what Paul did, but about what he wrote. This is most pertinent to the matter which I have in hand—namely, the confirmation of the universal and unquestionable truth of the Divine Scriptures, which have been delivered to us for our edification in the faith, not by unknown men, but by the apostles, and have on this account been received as the authoritative canonical standard. For if Peter did on that occasion what he ought to have done, Paul falsely affirmed that he saw him walking not uprightly, according to the truth of the gospel. For whoever does what he ought to do, walks uprightly. He therefore is guilty of falsehood who, knowing that another has done what he ought to have done, says that he has not done uprightly. If, then, Paul wrote what was true, it is true that Peter was not then walking uprightly, according to the truth of the gospel. He was therefore doing what he ought not to have done; and if Paul had himself already done something of the same kind, I would prefer to believe that, having been himself corrected, he could not omit the correction of his brother apostle, than to believe that he put down any false statement in his epistle; and if in any epistle of Paul this would be strange, how much more in the one in the preface of which he says, “The things which I write unto you, behold, before God, I lie not”!
8. For my part, I believe that Peter so acted on this occasion as to compel the Gentiles to live as Jews: because I read that Paul wrote this, and I do not believe that he lied. And therefore Peter was not acting uprightly. For it was contrary to the truth of the gospel, that those who believed in Christ should think that without those ancient ceremonies they could not be saved. This was the position maintained at Antioch by those of the circumcision who had believed; against whom Paul protested constantly and vehemently. As to Paul's circumcising of Timothy, performing a vow at Cenchrea, and undertaking on the suggestion of James at Jerusalem to share the performance of the appointed rites with some who had made a vow, it is manifest that Paul's design in these things was not to give to others the impression that he thought that by these observances salvation is given under the Christian dispensation, but to prevent men from believing that he condemned as no better than heathen idolatrous worship, those rites which God had appointed in the former dispensation as suitable to it, and as shadows of things to come. For this is what James said to him, that the report had gone abroad concerning him that he taught men “to forsake Moses.” This would be by all means wrong for those who believe in Christ, to forsake him who prophesied of Christ, as if they detested and condemned the teaching of him of whom Christ said, “Had ye believed Moses, you would have believed Me; for he wrote of Me.”
Source: Letters (New Advent)