Firmilian, Bishop of Caesarea in Cappadocia (A.D. 256) - Epistle LXXIV To Cyprian, Against the Letter of Stephen:

(7) "Moreover, all other heretics, if they have separated themselves from the Church of God, can have nothing of power or of grace, since all power and grace are established in the Church where the elders preside, who possess the power both of baptizing, and of imposition of hands, and of ordaining. For as a heretic may not lawfully ordain nor lay on hands, so neither may he baptize, nor do any thing holily or spiritually, since he is an alien from spiritual and deifying sanctity.

(14) "But if the spouse of Christ is one, which is the Catholic Church, it is she herself who alone bears sons of God. For there are not many spouses of Christ"

(16) "But what is the greatness of his error, and what the depth of his blindness, who says that remission of sins can be granted in the synagogues of heretics, and does not abide on the foundation of the one Church which was once based by Christ upon the rock, may be perceived from this, that Christ said to Peter alone, "Whatsoever thou shall bind on earth shall be bound in heaven, and whatsoever thou shall loose on earth shall be loosed in heaven." And again, in the Gospel, when Christ breathed on the apostles alone, saying, "Receive ye the Holy Ghost: whose soever sins ye remit they are remitted unto them, and whose soever sins ye retain they are retained." Therefore the power of remitting sins was given to the apostles, and to the churches which they, sent by Christ, established, and to the bishops who succeeded to them by vicarious ordination. But the enemies of the one Catholic Church in which we are, and the adversaries of us who have succeeded the apostles, asserting for themselves, in opposition to us, unlawful priesthoods, and setting up profane altars, what else are they than Korah, Dathan, and Abiram, profane with a like wickedness, and about to suffer the same punishments which they did, as well as those who agree with them, just as their partners and abettors perished with a like death to theirs?"