The thread I was in with them went on for 528 posts. The evidence I used spanned the Old Testament, New Testament, and the Early Church fathers. So, it wasn’t one or two quotes taken out of context. The thread started out being about the history of the 1054 AD Schism and the mutual lifting of the excommunications that happened in 1965.
I showed them pages of quotes from the ECF and from the Bible. For the ECF quotes, I showed them some that were prepared by Marcus Grodi. But they objected because the source of the quotes was a Catholic apologist.
So, I manually skimmed through 82 epistles and 12 of St. Cyprian’s Treatises to look for evidence for when and if Saint Cyprian spoke in favor of the Primacy of Peter. And I provided a clickable source link for every quote so that they could read the whole document that the quote came from if they desired to. But, they rejected all of these quotes. So, I picked one out from the batch of St. Cyprian quotes I gathered which I thought was the strongest statement about the Primacy of Peter. This is the quote:
“After such things as these, moreover, they still dare— a false bishop having been appointed for them by, heretics— to set sail and to bear letters from schismatic and profane persons to** the throne of Peter, and to the chief church whence priestly unity takes its source**; and not to consider that these were the Romans whose faith was praised in the preaching of the apostle, to whom faithlessness could have no access.” - St. Cyprian, Epistle 54
After many pages of them denying that the quotes I had been showing them were showing the Primacy of Peter, one of them finally told me that the ECF quotes I showed them were translated the wrong way. It was hard for me to believe this since the quotes all came from the Catholic Encyclopedia which is very meticulous in how they gather and present their information.
I showed them the following passages from the Bible and tried to explain them:
"And I tell you, you are Peter, and on this rock I will build my church, and the powers of death shall not prevail against it.** I will give you the keys of the kingdom of heaven, and whatever you bind on earth shall be bound in heaven, and whatever you loose on earth shall be loosed in heaven.**" - Matthew 16:18-19
I said, “The “keys” of authority that Jesus gives to Peter is even acknowledged in Heaven.”
"but I [Jesus] have prayed for you [Peter] that your faith may not fail; and when you have turned again, strengthen your brethren." - Luke 22:32
"He [Jesus] said to him the third time, 'Simon, son of John, do you love me?' Peter was grieved because he said to him the third time, 'Do you love me?' And he said to him, 'Lord, you know everything; you know that I love you.' Jesus said to him, 'Feed my sheep.'" - John 21:17
I said, “Are we not Jesus’ sheep? I don’t understand how heaven and earth can be interpreted to mean not universal.”
One replied with “Yes, absolutely I disagree. I am Orthodox. No one has universal authority but God.”
And I said, “Unless God appoints someone and grants him universal authority to lead God’s people, kind of like how God did with Moses in the Old Testament. Moses is an example of how there was a precedent for God appointing one man to lead all of God’s people.”