What exactly is the Catholic Church?
Irenaeus in ~180 a.d. answered that question as follows
Bk 3 [
Chapter 3 (
http://www.newadvent.org/fathers/0103303.htm) v 2-3 “Against Heresies”
2. Since, however, it would be very tedious, in such a volume as this, to reckon up the successions of all the Churches, we do put to confusion all those who, in whatever manner, whether by an evil self-pleasing, by vainglory, or by blindness and perverse opinion, assemble in unauthorized meetings; [we do this, I say,] by indicating that tradition derived from the apostles, of the very great, the very ancient, and universally known Church founded and organized at Rome by the two most glorious apostles, Peter and Paul; as also [by pointing out] the faith preached to men, which comes down to our time by means of the successions of the bishops. For it is a matter of necessity that every Churchshould agree with this Church, on account of its pre- eminent authority, inasmuch as the apostolic tradition has been preserved continuously by those faithful men] who exist everywhere.
3. The blessed apostles, then, having founded and built up the Church, committed into the hands of Linus the office of the episcopate. Of this Linus, Paul makes mention in the Epistles to Timothy. To him succeeded Anacletus; and after him, in the third place from the apostles, Clement was allotted the bishopric. This man, as he had seen the blessed apostles, and had been conversant with them, might be said to have the preaching of the apostles still echoing [in his ears], and their traditions before his eyes"
a few observations so far
- does Irenaeus say EVERY Church is to agree with Smyrna? Antioch? Alexandria? Jerusalem etc ? No. He writes, every Church EVERYWHERE is to agree with the bishop of Rome. And he names bishops of Rome in succession from Peter, down to his day,
- Those who follow this follow apostolic tradition.Ergo those who don’t keep to this understanding, are unfaithful because they don’t preserve the apostolic tradition, and they are the ones Irenaeus is writing against as heretics
- Who is Irenaeus? He is a Bishop, originally from Smyrna, which is today in Turkey. He was taught by Bp Polycarp of Smyrna, who WAS a disciple of St John. Irenaeus was made Bp of Lyon, which is today in France.
- Who is it that Irenaeus says taught him, what he teaches here? He says it came directly from the apostles through bishops in succession from Peter and Paul, and faithful men, who preserved the apostolic tradition FAITHFULLY down to his time.
Irenaeus also
- refutes opponants who argue the papacy is a later invention.
- refutes the notion that every Church EVERYWHERE agreeing with the bishop of Rome is a novelty of later invention.
concluding vs 3, Irenaeus finishes naming bishops down to his day in succession to Peter.
" Nor was he alone [in this], for there were many still remaining who had received instructions from the apostles. In the time of this Clement, no small dissension having occurred among the brethren at Corinth, the Church in Rome dispatched a most powerful letter to the Corinthians, exhorting them to peace, renewing their faith, and declaring the tradition which it had lately received from the apostles, proclaiming the one God, omnipotent, the Maker of heaven and earth, the Creator of man, who brought on the deluge, and called Abraham, who led the people from the land of Egypt, spoke with Moses, set forth the law, sent the prophets, and who has prepared fire for the devil and his angels. From this document, whosoever chooses to do so, may learn that He, the Father of our Lord Jesus Christ, was preached by the Churches, and may also understand the tradition of the Church, since this Epistle is of older date than these men who are now propagating falsehood, and who conjure into existence another god beyond the Creator and the Maker of all existing things. To this Clement there succeeded Evaristus. Alexander followed Evaristus; then, sixth from the apostles, Sixtus was appointed; after him, Telephorus, who was gloriously martyred then Hyginus; after him, Pius; then after him, Anicetus. Soter having succeeded Anicetus, Eleutherius does now, in the twelfth place from the apostles, hold the inheritance of the episcopate. In this order, andby this succession, the ecclesiastical tradition from the apostles, and the preaching of the truth, have come down to us. And this is most abundant proof that there is one and the same vivifying faith, which has been preserved in the Church from the apostles until now, and handed down in truth."
Just in case one observes, he doesn’t mention “Catholic Church” here, Irenaeus has already identified what Church he is defending.
Bk 1 ch 10 v 3
newadvent.org/fathers/0103110.htm
Bk 3 ch 4 (opening to ch 4)
newadvent.org/fathers/0103304.htm