- — St. Ignatius of Antioch, (A.D. 50-107)
— St. Irenæus of Lyons, (A.D. 125-202)
— The Martyrdom of Polycarp, (A.D. 147)
— St. Clement of Alexandria, (A.D. 150-220)
— Tertullian, (A.D. 160-218)
— St. Hippolytus of Rome, (A.D. 170-236)
You must all follow the bishop as Jesus Christ follows the Father and the presbytery as you would the Apostles. Reverence the deacons as you would the command of God. Let no one do anything of concern to the Church without the bishop. Let that be considered a valid Eucharist which is celebrated by the bishop, or by one whom he appoints.
Wherever the bishop appears, let the people be there; just as wherever Jesus Christ is, there is the Catholic Church. [Earliest instant of the word Catholic]
Nor is it permitted without the bishop either to baptize or to celebrate the agape; but whatever he approves, this too is pleasing to God, so that whatever is done will be secure and valid.
St. Ignatius of Antioch, to the Smyrnaeans 8:1; Chapter 10,138 [ A.D. 107]
It is good to regard God and the bishop. Who so honors the bishop, honors God; but he who does something and hides it from the bishop, worships the devil."
St. Ignatius of Antioch, to the Smyrnaeans 
The Faith of Catholics, Volume 1, page 15-16
The Catholic Church possesses one and the same faith throughout the whole world, as we have already said.
Against Heresies 1:10 [ A.D. 189]
Since therefore we have such proofs, it is not necessary to seek the truth among others which it is easy to obtain from the Church; since the Apostles, like a rich man [depositing his money] in a bank, lodged in her hands most copiously all things pertaining to the truth: so that every man, whosoever will, can draw from Her the water of life. For She is the entrance to life; all others are thieves and robbers. On this account, we are bound to avoid them, and to make choice of the things pertaining to the Church with the utmost diligence, and to lay hold of the tradition of the truth.
Suppose there should arise a dispute relative to some important question among us.
- Should we not have recourse to the most ancient churches with which the Apostles held constant intercourse, and learn from them what is certain and clear in regard to the present question?
- For how should it be if the Apostles themselves had not left us writings?
- Would it not be necessary [in that case] to follow the course of the tradition which they handed down to those to whom they entrusted to the churches?
Against Heresies 3:4
When finally he concluded his prayer, after remembering all who had at any time come his way — small folk and great folk, distinguished and undistinguished, and the whole Catholic Church throughout the world — the time for departure came.
So they placed him on an ass, and brought him into the city on a great Sabbath.
The Martyrdom of Polycarp [ A.D. 110]
A multitude of other pieces of advice to particular persons is written in the holy books: some for presbyters, some for bishops and deacons; and others for widows, of whom we shall have opportunity to speak elsewhere.
The Instructor of Children 3:12:97:2 [ A.D. 191]
Even here in the Church the gradations of bishops, presbyters, and deacons happen to be imitations, in my opinion, of the angelic glory and of that arrangement which, the Scriptures say, awaits those who have followed in the footsteps of the Apostles and who have lived in complete righteousness according to the Gospel.
Stromateis 6:13:107:2 [ A.D. post 202]
- Where was Marcion then, that shipmaster of Pontus, the zealous student of Stoicism?
- Where was Valentinus then, the disciple of Platonism?
For it is evident that those men lived not so long ago — in the reign of Antoninus for the most part — and that they at first were believers in the doctrine of the Catholic Church, in the Church of Rome under the episcopate of the blessed Eleutherus, until on account of their ever restless curiosity, with which they even infected the brethren, they were more than once expelled.
The Prescription Against Heretics 22,30 [ A.D. 200]
When a deacon is to be ordained, he is chosen after the fashion of those things said above, the bishop alone in like manner imposing his hands upon him as we have prescribed. In the ordaining of a deacon, this is the reason why the bishop alone is to impose his hands upon him: He is not ordained to the priesthood, but to serve the bishop and to fulfill the bishop's command. He has no part in the council of the clergy, but is to attend to his own duties and is to acquaint the bishop with such matters as are needful.
On a presbyter [priest], however, let the presbyters impose their hands because of the common and like Spirit of the clergy. Even so, the presbyter has only the power to receive [the Spirit], and not the power to give [the Spirit]. That is why a presbyter does not ordain the clergy; for at the ordaining of a presbyter, he but seals while the bishop ordains.
Apostolic Tradition 9 [ A.D. c. 215]
The word Catholic means universal, because Our Blessed Lord came to save all mankind from the fall of Adam and Eve to the last person born up to His Glorious Second Coming.
The Church's Scriptures that support the Catholicity of the Church:
The Mass foretold in the Old Testament:
10 Who is there even among you who would shut the doors, So that you would not kindle fire on My altar in vain? I have no pleasure in you," Says the Lord of hosts, "Nor will I accept an offering from your hands. 11 For from the rising of the sun, even to its going down, My name shall be great among the Gentiles; In every place incense shall be offered to My name, And a pure offering; For My name shall be great among the nations," Says the Lord of hosts.
14 And this gospel of the kingdom will be preached throughout the whole world, as a testimony to all nations; and then the end will come.
Jesus Commissions the Disciples
15 And he said to them, "Go into all the world and preach the gospel to the whole creation. 16 He who believes and is baptized will be saved; but he who does not believe will be condemned.
The Ascension of Jesus
8 But you shall receive power when the Holy Spirit has come upon you; and you shall be my witnesses in Jerusalem and in all Judea and Samaria and to the end of the earth."
Salvation Is for All
17 So faith comes from what is heard, and what is heard comes by the preaching of Christ. 18 But I ask, have they not heard? Indeed they have; for "Their voice has gone out to all the earth, and their words to the ends of the world."