Is it possible to be a heretic knowingly?
Disciple Now I understand differently from before the distinction between a knowingly pertinacious and an unknowingly pertinacious person and likewise [the distinction] between a knowingly heretical and an unknowingly heretical person. And therefore although I thought before that no one was knowingly pertinacious or knowingly a heretic, now it seems to me that everyone pertinacious in error and every heretic is knowingly pertinacious and knowingly a heretic and absolutely no one is unknowingly so. This can be proved by the following argument. For someone to be catholic and faithful it is enough that he has implicit faith. This seems to be clear from the example of the centurion Cornelius, about whom we read in Acts 10. He was faithful before he had explicit faith concerning Christ because he was just and feared God and as a result did have at least implicit faith. And thus implicit faith suffices for someone to be catholic and faithful. But whoever is not knowingly pertinacious or knowingly a heretic in the way set out earlier has implicit faith because, from the fact that he does not think that he is erring against the christian faith, he believes that the whole christian faith is true even if he errs in some particular. Now he who believes that the whole christian faith is true has implicit faith. He is, therefore, catholic and faithful and as a result is neither pertinacious nor a heretic. This argument is confirmed because he who believes that the whole christian faith is true has faith in every truth pertaining to the christian faith; he who has faith in every truth pertaining to the christian faith, however, is not a heretic and as a result is not pertinacious. But whoever is not knowingly pertinacious nor knowingly a heretic believes that the whole christian faith is true; he has faith, therefore, in every truth pertaining to christian faith and consequently is in no way a heretic or pertinacious.
Master Those objections are brought forward mainly to prove that no one is unknowingly a heretic.
Disciple That is so.
Master Let us therefore put aside speaking about someone pertinacious and let it be enough to talk about a heretic.
Disciple This is acceptable because he who can see how anyone can be unknowingly a heretic will not doubt that someone will be able to be unknowingly pertinacious.
Master A distinction is made among those who are unknowingly heretics. For some people are or can be unknowingly heretics because they knowingly and explicitly think that some assertions written in divine scripture in those exact words do not pertain to christian faith. The Manichees were like this; according to Isidore, as is reported in 24. q. 3. c. Quidam autem [col.1001], they rejected the Old Testament and accepted the New only in part and in this way thought that they were catholic and faithful christians; and they were unknowingly heretics, therefore, because they maintained that the assertions contained in the Old Testament do not pertain to christian faith. Certain people are unknowingly heretics, however, who do not doubt that any assertion pertaining to the christian faith and found in divine scripture in those exact words is true because they accept the whole of divine scripture, but they do not believe, on the other hand, that some assertions that follow from them are true, because they do not think that they do follow from them, for the reason that they understand the divine scriptures in a sense other than the holy spirit, by whom they are written, demands. Some people irrevocably believe, moreover, that assertions contrary [to catholic faith] are true; they should be considered heretics, therefore, even though they believe in general that the whole christian faith is true.
part 1, book 4, chapters 1-5
Text and translation by John Scott.
Copyright © 1999, The British Academy.