4 You do not require me to teach you in what sense the apostle says, “To the Jews I became as a Jew, that I might gain the Jews,” and other such things in the same passage, which are to be ascribed to the compassion of pitying love, not the artifices of intentional deceit. For he that ministers to the sick becomes as if he were sick himself; not, indeed, falsely pretending to be under the fever, but considering, with the mind of one truly sympathizing, what he would wish done for himself if he were in the sick man's place. Paul was indeed a Jew; and when he had become a Christian, he had not abandoned those Jewish sacraments which that people had received in the right way, and for a certain appointed time. Therefore, even although he was an apostle of Christ, he took part in observing these; but with this view, that he might show that they were in no wise hurtful to those who, even after they had believed in Christ, desired to retain the ceremonies which by the law they had learned from their fathers; provided only that they did not build on these their hope of salvation, since the salvation which was foreshadowed in these has now been brought in by the Lord Jesus. For the same reason, he judged that these ceremonies should by no means be made binding on the Gentile converts, because, by imposing a heavy and superfluous burden, they might turn aside from the faith those who were unaccustomed to them.
5. The thing, therefore, which he rebuked in Peter was not his observing the customs handed down from his fathers— which Peter, if he wished, might do without being chargeable with deceit or inconsistency, for, though now superfluous, these customs were not hurtful to one who had been accustomed to them— but his compelling the Gentiles to observe Jewish ceremonies, which he could not do otherwise than by so acting in regard to them as if their observance was, even after the Lord's coming, still necessary to salvation, against which truth protested through the apostolic office of Paul. Nor was the Apostle Peter ignorant of this, but he did it through fear of those who were of the circumcision. Manifestly, therefore, Peter was truly corrected, and Paul has given a true narrative of the event, unless, by the admission of a falsehood here, the authority of the Holy Scriptures given for the faith of all coming generations is to be made wholly uncertain and wavering. For it is neither possible nor suitable to state within the compass of a letter how great and how unutterably evil must be the consequences of such a concession. It might, however, be shown seasonably, and with less hazard, if we were conversing together.
6. Paul had forsaken everything peculiar to the Jews that was evil, especially this: “That, being ignorant of God's righteousness, and going about to establish their own righteousness, they had not submitted themselves unto the righteousness of God.” In this, moreover, he differed from them: that after the passion and resurrection of Christ, in whom had been given and made manifest the mystery of grace, according to the order of Melchizedek, they still considered it binding on them to celebrate, not out of mere reverence for old customs, but as necessary to salvation, the sacraments of the old economy, which were indeed at one time necessary, else had it been unprofitable and vain for the Maccabees to suffer martyrdom, as they did, for their adherence to them. Lastly, in this also Paul differed from the Jews: that they persecuted the Christian preachers of grace as enemies of the law. These and all similar errors and sins he declares that he “counted but loss and dung that he might win Christ;” but he does not, in so saying, disparage the ceremonies of the Jewish law, if only they were observed after the custom of their fathers, in the way in which he himself observed them, without regarding them as necessary to salvation, and not in the way in which the Jews affirmed that they must be observed, nor in the exercise of deceptive dissimulation such as he had rebuked in Peter. For if Paul observed these sacraments in order, by pretending to be a Jew, to gain the Jews, why did he not also take part with the Gentiles in heathen sacrifices, when to them that were without law he became as without law, that he might gain them also? The explanation is found in this, that he took part in the Jewish sacrifices, as being himself by birth a Jew; and that when he said all this which I have quoted, he meant, not that he pretended to be what he was not, but that he felt with true compassion that he must bring such help to them as would be needful for himself if he were involved in their error. Herein he exercised not the subtlety of a deceiver, but the sympathy of a compassionate deliverer. In the same passage the apostle has stated the principle more generally: “To the weak became I as weak, that I might gain the weak; I am made all things to all men, that I might by all means save some,” — the latter clause of which guides us to understand the former as meaning that he showed himself one who pitied the weakness of another as much as if it had been his own. For when he said, “Who is weak, and I am not weak?” he did not wish it to be supposed that he pretended to suffer the infirmity of another, but rather that he showed it by sympathy.
7. Wherefore I beseech you, apply to the correction and emendation of that book a frank and truly Christian severity, and chant what the Greeks call παλινῴδια. For incomparably more lovely than the Grecian Helen is Christian truth: In her defence, our martyrs have fought against Sodom with more courage than the heroes of Greece displayed against Troy for Helen's sake. I do not say this in order that you may recover the faculty of spiritual sight, — far be it from me to say that you have lost it!— but that, having eyes both clear and quick in discernment, you may turn them towards that from which, in unaccountable dissimulation, you have turned them away, refusing to see the calamitous consequences which would follow on our once admitting that a writer of the divine books could in any part of his work honourably and piously utter a falsehood.
Source: Letters (New Advent)