“Let us not listen to those who deny that the Church of God is able to forgive all sins. They are wretched indeed, because they do not recognize in Peter the rock (3) and they refuse to believe that the keys of the kingdom of heaven, lost from their own hands, have been given to the Church. These are people who condemn as adulteresses widows who marry, and boast that theirs is a purity superior to the teaching of the Apostles!” (Augustine, Against the Letter of Mani, AD 396 aut 397)
“For if the lineal succession of bishops is to be taken into account, with how much more certainty and benefit to the Church do we reckon back till we reach Peter himself, to whom, as bearing in a figure the whole Church, the Lord said: ‘Upon this rock will I build my Church, and the gates of hell shall not prevail against it!’ The successor of Peter was Linus, and his successors in unbroken continuity were these: ‑Clement, Anacletus, Evaristus, Alexander, Sixtus, Telesphorus, Iginus, Anicetus, Pius, Soter, Eleutherius, Victor, Zephirinus, Calixtus, Urbanus, Pontianus, Antherus, Fabianus, Cornelius, Lucius, Stephanus, Xystus, Dionysius, Felix, Eutychianus, Gaius, Marcellinus, Marcellus, Eusebius, Miltiades, Sylvester, Marcus, Julius, Liberius, Damasus, and Siricius, whose successor is the present Bishop Anastasius. In this order of succession no Donatist bishop is found” (Letters of Augustine 53, 2 in The Nicene and Post-Nicene Fathers 1st series, 1:298).
THE CHURCH ESTABLISHED BY CHRIST MUST BE HEADED BY DIRECT SUCCESSOR OF PETER .
Here is one for you.
“If all men throughout the world were such as you most vainly accuse them of having been, what has the chair of the Roman church done to you, in which Peter sat, and in which Anastasius sits today?” [Against the Letters of Petilani 2:118 [A.D. 402]
“Whosoever shall have separated himself from the Catholic Church, no matter how praiseworthy such a person may fancy his life has been, yet for that one crime of having cut himself off from the unity of Christ he shall not have eternal life, buth the wrath of God shall abide with him for ever.” St Augustine of Hippo (“Letter 141” c. early 5th century)