Iz povijesti KC:A letter written by Ignatius to Christians in Smyrna [1] around 106 A.D. is the earliest surviving witness to the use of the term "Catholic Church" Letter to the Smyrnaeans, 8. By "Catholic Church" Ignatius designated the Christian Church in its universal aspect, excluding heretics, such as those who disavow "the Eucharist to be the flesh of our Saviour Jesus Christ, which suffered for our sins, and which the Father, of His goodness, raised up again" (Smyrnaeans, 7). He called such people "beasts in the shape of men, whom you must not only not receive, but, if it be possible, not even meet with" (Smyrnaeans, 4). The term is also used in the Martyrdom of Polycarp in 155 and in the Muratorian fragment, about 177.St Cyril of Jerusalem (circa 315-386) urged those he was instructing in the Christian faith: "If ever thou art sojourning in cities, inquire not simply where the Lord's House is (for the other sects of the profane also attempt to call their own dens houses of the Lord), nor merely where the Church is, but where is the Catholic Church. For this is the peculiar name of this Holy Church, the mother of us all, which is the spouse of our Lord Jesus Christ, the Only-begotten Son of God" (Catechetical Lectures, XVIII, 26).
[2]The term "Catholic Christians" entered Roman Imperial law when
Theodosius I, Emperor from 379 to 395, reserved that name for adherents of "that religion which was delivered to the Romans by the divine Apostle Peter, as it has been preserved by faithful tradition and which is now professed by the Pontiff (Pope) Damasus and by Peter, Bishop of Alexandria ...as for the others, since in our judgement they are foolish madmen, we decree that they shall be branded with the ignominious name of heretics, and shall not presume to give their conventicles the name of churches." This law of
27 February 380 was included in Book 16 of the
Codex Theodosianus.
[3] It established Catholic Christianity as the official religion of the Roman Empire.
The use of the term "Catholic" to distinguish the "true" Church from heretical groups is found also in Augustine who wrote:
"In the Catholic Church, there are many other things which most justly keep me in her bosom. The consent of peoples and nations keeps me in the Church; so does her authority, inaugurated by miracles, nourished by hope, enlarged by love, established by age. The succession of priests keeps me, beginning from the very seat of the Apostle Peter, to whom the Lord, after His resurrection, gave it in charge to feed His sheep (Jn 21:15-19), down to the present episcopate.
"And so, lastly, does the very name of Catholic, which, not without reason, amid so many heresies, the Church has thus retained; so that, though all heretics wish to be called Catholics, yet when a stranger asks where the Catholic Church meets, no heretic will venture to point to his own chapel or house.
"Such then in number and importance are the precious ties belonging to the Christian name which keep a believer in the Catholic Church, as it is right they should ... With you, where there is none of these things to attract or keep me... No one shall move me from the faith which binds my mind with ties so many and so strong to the Christian religion... For my part, I should not believe the gospel except as moved by the authority of the Catholic Church."
— St. Augustine (354–430):
Against the Epistle of Manichaeus called Fundamental, chapter 4: Proofs of the Catholic Faith
[4].
A contemporary of Augustine,
St. Vincent of Lerins, wrote in 434 under the pseudonym Peregrinus a work known as the
Commonitoria ("Memoranda"). While insisting that, like the human body, Church doctrine develops while truly keeping its identity (sections 54-59, chapter XXIII), he stated: "[I]n the Catholic Church itself, all possible care must be taken, that we hold that faith which has been believed everywhere, always, by all. For that is truly and in the strictest sense 'Catholic,' which, as the name itself and the reason of the thing declare, comprehends all universally. This rule we shall observe if we follow universality, antiquity, consent. We shall follow universality if we confess that one faith to be true, which the whole Church throughout the world confesses; antiquity, if we in no wise depart from those interpretations which it is manifest were notoriously held by our holy ancestors and fathers; consent, in like manner, if in antiquity itself we adhere to the consentient definitions and determinations of all, or at the least of almost all priests and doctors" (section 6, end of chapter II).