A Rule for Telling the Catholic Faith from Heresy

So I have often asked, earnestly and carefully, a great many men outstanding for holiness and learning how, and by what sure and, so to speak, universal rule, I might be able to tell the truth of the catholic faith from the falsehood of heretical corruption. And I have always received, from almost every one of them, an answer to this effect. Whether I or anyone else wishes to detect the frauds and avoid the snares of heretics as they arise, and to remain sound and whole in the catholic faith, we must, with the Lord’s help, fortify our own belief in two ways: first, by the authority of the divine law, and then by the tradition of the catholic church.

But here someone may ask: “Since the canon of Scripture is complete, and is sufficient of itself for everything, and more than sufficient, what need is there to join to it the authority of the church’s interpretation?” For this reason. Because of the depth of Holy Scripture, not everyone takes it in one and the same sense. One person understands its words one way, another another, so that it seems capable of as many interpretations as there are interpreters. Novatian explains it one way, Sabellius another, Donatus another; Arius, Eunomius, and Macedonius another; Photinus, Apollinaris, and Priscillian another; Jovinian, Pelagius, and Caelestius another; and lastly Nestorius another. Therefore, because of the great tangle of so many different errors, it is very necessary that the rule for rightly understanding the prophets and apostles be framed by the standard of the church’s catholic interpretation. [a]

Moreover, in the catholic church itself we must take every possible care to hold that faith which has been believed everywhere, always, and by all. For that is truly and in the strictest sense “catholic” which, as the name itself and the nature of the thing declare, takes in everything universally. We will keep this rule if we follow universality, antiquity, and consent. We follow universality if we confess as true that one faith which the whole church throughout the world confesses. We follow antiquity if we in no way depart from those interpretations which it is plain our holy ancestors and fathers openly held. We follow consent, in the same way, if within antiquity itself we hold to the agreed definitions and decisions of all, or at least of almost all, the priests and teachers. [c]