If only this otherwise helpful and concise statement could aid those grappling with the question in deciding which of Catholicism or Eastern Orthodoxy is that “Christianity of history”…
For me it came down to “the seat of Peter”
Clement of Alexandria
“[T]he blessed Peter, the chosen, the preeminent, the first among the disciples, for whom alone with himself the Savior paid the tribute [Matthew 17:27], quickly grasped and understood their meaning. And what does he say? ‘Behold, we have left all and have followed you’ [Matthew 19:27, Mark 10:28]" (Who Is the Rich Man That Is Saved? 21:3-5 - 200 AD)
Tertullian
“For though you think that heaven is still shut up, remember that the Lord left the keys of it to Peter here, and through him to the Church, which keys everyone will carry with him if he has been questioned and made a confession [of faith]" (Antidote Against the Scorpion 10 - 211 AD)
“[T]he Lord said to Peter, ‘On this rock I will build my Church, I have given you the keys of the kingdom of heaven [and] whatever you shall have bound or loosed on earth will be bound or loosed in heaven’ [Matthew 16:18-19]. . . . Upon you, he says, I will build my Church; and I will give to you the keys, not to the Church" (Modesty 21:9-10 - 220 AD)
The Letter of Clement to James
“Be it known to you, my lord, that Simon [Peter], who, for the sake of the true faith, and the most sure foundation of his doctrine, was set apart to be the foundation of the Church, and for this end was by Jesus himself, with his truthful mouth, named Peter, the first fruits of our Lord, the first of the apostles; to whom first the Father revealed the Son; whom the Christ, with good reason, blessed; the called, and elect" (Letter of Clement to James 2 - 221 AD)
Origen
“*f we were to attend carefully to the Gospels, we should also find, in relation to those things which seem to be common to Peter . . . a great difference and a preeminence in the things [Jesus] said to Peter, compared with the second class [of apostles]. For it is no small difference that Peter received the keys not of one heaven but of more, and in order that whatsoever things he binds on earth may be bound not in one heaven but in them all, as compared with the many who bind on earth and loose on earth, so that these things are bound and loosed not in [all] the heavens, as in the case of Peter, but in one only; for they do not reach so high a stage with power as Peter to bind and loose in all the heavens” (Commentary on Matthew 13:31 - 248 AD)
Cyprian of Carthage
“The Lord says to Peter: ‘I say to you,’ he says, ‘that you are Peter, and upon this rock I will build my Church.’ . . . On him [Peter] he builds the Church, and to him he gives the command to feed the sheep [John 21:17], and although he assigns a like power to all the apostles, yet he founded a single chair [cathedra], and he established by his own authority a source and an intrinsic reason for that unity. Indeed, the others were that also which Peter was *, but a primacy is given to Peter, whereby it is made clear that there is but one Church and one chair. So too, all [the apostles] are shepherds, and the flock is shown to be one, fed by all the apostles in single-minded accord. If someone does not hold fast to this unity of Peter, can he imagine that he still holds the faith? If he [should] desert the chair of Peter upon whom the Church was built, can he still be confident that he is in the Church?” (The Unity of the Catholic Church 4; 1st edition - 251 AD)
Cyril of Jerusalem
“The Lord is loving toward men, swift to pardon but slow to punish. Let no man despair of his own salvation. Peter, the first and foremost of the apostles, denied the Lord three times before a little servant girl, but he repented and wept bitterly" (Catechetical Lectures 2:19 - 350 AD)
“[Simon Magus] so deceived the city of Rome that Claudius erected a statue of him. . . . While the error was extending itself, Peter and Paul arrived, a noble pair and the rulers of the Church, and they set the error aright. . . . [T]hey launched the weapon of their like-mindedness in prayer against the Magus, and struck him down to earth. It was marvelous enough, and yet no marvel at all, for Peter was there—he that carries about the keys of heaven [Matthew 16:19]" (Catechetical Lectures 6:14 - 350 AD)
“In the power of the same Holy Spirit, Peter, both the chief of the apostles and the keeper of the keys of the kingdom of heaven, in the name of Christ healed Aeneas the paralytic at Lydda, which is now called Diospolis [Acts 9:32-34]" (Catechetical Lectures 17:27 - 350 AD)
In the end, is Peter the Rock who Christ founded his church on or isn’t he? At least for me this settled the issue. From what I’ve read about the EOC, their issue was regarding the
primacy* of Rome, none doubt that Peter was given the Keys.
Consider this, they lack a Bishop and are unable to call an Ecumenical Council. Rome hasn’t got this issue.*