3 I have been reading also some writings, ascribed to you, on the Epistles of the Apostle Paul. In reading your exposition of the Epistle to the Galatians, that passage came to my hand in which the Apostle Peter is called back from a course of dangerous dissimulation. To find there the defence of falsehood undertaken, whether by you, a man of such weight, or by any author (if it is the writing of another), causes me, I must confess, great sorrow, until at least those things which decide my opinion in the matter are refuted, if indeed they admit of refutation. For it seems to me that most disastrous consequences must follow upon our believing that anything false is found in the sacred books: that is to say, that the men by whom the Scripture has been given to us, and committed to writing, did put down in these books anything false. It is one question whether it may be at any time the duty of a good man to deceive; but it is another question whether it can have been the duty of a writer of Holy Scripture to deceive: nay, it is not another question— it is no question at all. For if you once admit into such a high sanctuary of authority one false statement as made in the way of duty, there will not be left a single sentence of those books which, if appearing to any one difficult in practice or hard to believe, may not by the same fatal rule be explained away, as a statement in which, intentionally, and under a sense of duty, the author declared what was not true.
4. For if the Apostle Paul did not speak the truth when, finding fault with the Apostle Peter, he said: “If you, being a Jew, livest after the manner of Gentiles, and not as do the Jews, why do you compel the Gentiles to live as do the Jews?”— if, indeed, Peter seemed to him to be doing what was right, and if, notwithstanding, he, in order to soothe troublesome opponents, both said and wrote that Peter did what was wrong; — if we say thus, what then shall be our answer when perverse men such as he himself prophetically described arise, forbidding marriage, if they defend themselves by saying that, in all which the same apostle wrote in confirmation of the lawfulness of marriage, he was, on account of men who, through love for their wives, might become troublesome opponents, declaring what was false,— saying these things, forsooth, not because he believed them, but because their opposition might thus be averted? It is unnecessary to quote many parallel examples. For even things which pertain to the praises of God might be represented as piously intended falsehoods, written in order that love for Him might be enkindled in men who were slow of heart; and thus nowhere in the sacred books shall the authority of pure truth stand sure. Do we not observe the great care with which the same apostle commends the truth to us, when he says: “And if Christ be not risen, then is our preaching vain, and your faith is also vain: yea, and we are found false witnesses of God; because we have testified of God that He raised up Christ; whom He raised not up, if so be that the dead rise not.” If any one said to him, “Why are you so shocked by this falsehood, when the thing which you have said, even if it were false, tends very greatly to the glory of God?” would he not, abhorring the madness of such a man, with every word and sign which could express his feelings, open clearly the secret depths of his own heart, protesting that to speak well of a falsehood uttered on behalf of God, was a crime not less, perhaps even greater, than to speak ill of the truth concerning Him? We must therefore be careful to secure, in order to our knowledge of the divine Scriptures, the guidance only of such a man as is imbued with a high reverence for the sacred books, and a profound persuasion of their truth, preventing him from flattering himself in any part of them with the hypothesis of a statement being made not because it was true, but because it was expedient, and making him rather pass by what he does not understand, than set up his own feelings above that truth. For, truly, when he pronounces anything to be untrue, he demands that he be believed in preference, and endeavours to shake our confidence in the authority of the divine Scriptures.
5. For my part, I would devote all the strength which the Lord grants me, to show that every one of those texts which are wont to be quoted in defence of the expediency of falsehood ought to be otherwise understood, in order that everywhere the sure truth of these passages themselves may be consistently maintained. For as statements adduced in evidence must not be false, neither ought they to favour falsehood. This, however, I leave to your own judgment. For if you apply more thorough attention to the passage, perhaps you will see it much more readily than I have done. To this more careful study that piety will move you, by which you discern that the authority of the divine Scriptures becomes unsettled (so that every one may believe what he wishes, and reject what he does not wish) if this be once admitted, that the men by whom these things have been delivered unto us, could in their writings state some things which were not true, from considerations of duty; unless, perchance, you propose to furnish us with certain rules by which we may know when a falsehood might or might not become a duty. If this can be done, I beg you to set forth these rules with reasonings which may be neither equivocal nor precarious; and I beseech you by our Lord, in whom Truth was incarnate, not to consider me burdensome or presumptuous in making this request. For a mistake of mine which is in the interest of truth cannot deserve great blame, if indeed it deserves blame at all, when it is possible for you to use truth in the interest of falsehood without doing wrong.
Source: Letters (New Advent)