In the original Catholic, i.e. “Catholics.” Heresies might become widespread—the Arian heresy, indeed, counted numerous adherents in the fourth, fifth, and sixth centuries—but they took their rise in some member or other of the ecclesiastical body, in some one of the many local churches which together made up the one œcumenical church. On the other hand, the primitive teaching, received from the apostolic age, had been delivered without difference in every place to which it had penetrated. It was acknowledged and established before sects and heresies; its original was divine, theirs only human; it rested on the rock of Christ’s authority, speaking through His apostles, whilst they were built on the sands of preeminence in sophistry and captious interpretation; it was for all times and places, therefore, but they were only for a season. In this belief those who clave to the teaching of the apostles claimed for themselves the name of “Catholics,” and for the œcumenical church of which they were members that of “Catholic and Apostolic.” To avoid any misunderstanding, I have used the term “orthodox,” which will stand very well for “Catholic,” inasmuch as “the right faith” is for all, without difference, to hold—in a word, universal, or, as it is in Greek, καθ᾽ ὅλου (whence καθολικός, Catholicus, Catholic).
Editorial footnote · Exposition of the Christian Faith, Chapter V., editorial note cite_note-1 · Original source