15 It is further said in your letter: “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.” Again I say: Since you are a bishop, a teacher in the Churches of Christ, if you would prove what you assert, receive any Jew who, after having become a Christian, circumcises any son that may be born to him, observes the Jewish Sabbath, abstains from meats which God has created to be used with thanksgiving, and on the evening of the fourteenth day of the first month slays a paschal lamb; and when you have done this, or rather, have refused to do it (for I know that you are a Christian, and will not be guilty of a profane action), you will be constrained, whether willingly or unwillingly, to renounce your opinion; and then you will know that it is a more difficult work to reject the opinion of others than to establish your own. Moreover, lest perhaps we should not believe your statement, or, I should rather say, understand it (for it is often the case that a discourse unduly extended is not intelligible, and is less censured by the unskilled in discussion because its weakness is not so easily perceived), you inculcate your opinion by reiterating the statement in these words: “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 to 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 dispensation; 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.”
16. We have learned from you what evil things peculiar to the Jews Paul had abandoned; let us now learn from your teaching what good things which were Jewish he retained. You will reply: “The ceremonial observances in which they continued to follow the practice of their fathers, in the way in which these were complied with by Paul himself, without believing them to be at all necessary to salvation.” I do not fully understand what you mean by the words, “without believing them to be at all necessary to salvation.” For if they do not contribute to salvation, why are they observed? And if they must be observed, they by all means contribute to salvation; especially seeing that, because of observing them, some have been made martyrs: for they would not be observed unless they contributed to salvation. For they are not things indifferent— neither good nor bad, as philosophers say. Self-control is good, self-indulgence is bad: between these, and indifferent, as having no moral quality, are such things as walking, blowing one's nose, expectorating phlegm, etc. Such an action is neither good nor bad; for whether you do it or leave it undone, it does not affect your standing as righteous or unrighteous. But the observance of legal ceremonies is not a thing indifferent; it is either good or bad. You say it is good. I affirm it to be bad, and bad not only when done by Gentile converts, but also when done by Jews who have believed. In this passage you fall, if I am not mistaken, into one error while avoiding another. For while you guard yourself against the blasphemies of Porphyry, you become entangled in the snares of Ebion; pronouncing that the law is binding on those who from among the Jews have believed. Perceiving, again, that what you have said is a dangerous doctrine, you attempt to qualify it by words which are only superfluous: viz., “The law must be observed not from any belief, such as prompted the Jews to keep it, that this is necessary to salvation, and not in any misleading dissimulation such as Paul reproved in Peter.”
17. Peter therefore pretended to keep the law; but this censor of Peter boldly observed the things prescribed by the law. The next words of your letter are these: “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 rites as being himself 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.” A triumphant vindication of Paul! You prove that he did not pretend to share the error of the Jews, but was actually involved in it; and that he refused to imitate Peter in a course of deception, dissembling through fear of the Jews what he really was, but without reserve freely avowed himself to be a Jew. Oh, unheard of compassion of the apostle! In seeking to make the Jews Christians, he himself became a Jew! For he could not have persuaded the luxurious to become temperate if he had not himself become luxurious like them; and could not have brought help, in his compassion, as you say, to the wretched, otherwise than by experiencing in his own person their wretchedness! Truly wretched, and worthy of most compassionate lamentation, are those who, carried away by vehemence of disputation, and by love for the law which has been abolished, have made Christ's apostle to be a Jew. Nor is there, after all, a great difference between my opinion and yours: for I say that both Peter and Paul, through fear of the believing Jews, practised, or rather pretended to practise, the precepts of the Jewish law; whereas you maintain that they did this out of pity, “not with the subtlety of a deceiver, but with the sympathy of a compassionate deliverer.” But by both this is equally admitted, that (whether from fear or from pity) they pretended to be what they were not. As to your argument against our view, that he ought to have become to the Gentiles a Gentile, if to the Jews he became a Jew, this favours our opinion rather than yours: for as he did not actually become a Jew, so he did not actually become a heathen; and as he did not actually become a heathen, so he did not actually become a Jew. His conformity to the Gentiles consisted in this, that he received as Christians the uncircumcised who believed in Christ, and left them free to use without scruple meats which the Jewish law prohibited; but not, as you suppose, in taking part in their worship of idols. For “in Christ Jesus, neither circumcision avails anything, nor uncircumcision, but the keeping of the commandments of God.”
Source: Letters (New Advent)