Firmilian of Caesarea, Letter to Cyprian 17
I am justly indignant at Stephen's stupidity, which is so open and manifest. He boasts of his episcopal see and claims to hold Peter's succession, upon whom the foundations of the Church are laid. Yet he introduces many other rocks and establishes new buildings for many churches, while defending baptism there by his own authority. Those who are baptized doubtless complete the Church's number. Whoever approves their baptism confirms that the Church exists among the baptized as well. He fails to understand that he obscures and, in a sense, abolishes the truth of the Christian rock by betraying and deserting unity. Meanwhile, the Apostle testifies that the Jews, though blinded by ignorance and bound by a most serious crime, have zeal for God. Stephen, who proclaims he holds Peter's chair by succession, is stirred by no zeal against heretics. He concedes to them not moderate but maximum power of grace, so that he says and asserts they wash away the filth of the old man through the sacrament of baptism, forgive ancient deadly sins, make them sons of God by heavenly regeneration, and restore them to eternal life by the sanctification of the divine washing. When he thus grants and attributes such great and heavenly gifts of the Church to heretics, what else does he do but communicate with those whose grace he defends and vindicates? And he doubts in vain whether he also consents to the rest and becomes a partaker with them, so that he agrees with them, mixes prayers equally with them, and establishes a common altar and sacrifice.
Latin
Atque ego in hac parte juste indignor ad hanc tam apertam et manifestam Stephani stultitiam, quod qui sic de episcopatus sui loco gloriatur et se successionem Petri tenere contendit, super quem fundamenta Ecclesiae collocata sunt, multas alias petras inducat et ecclesiarum multarum nova aedificia constituat, dum esse illic baptisma sua auctoritate defendit. Nam qui baptizantur complent sine dubio Ecclesiae numerum. Qui autem baptisma eorum probat, de baptizatis et Ecclesiam illic esse confirmat. Nec intelligit obfuscari a se et quodam modo aboleri christianae petrae veritatem qui sic prodit et deserit unitatem. Judaeos tamen, quamvis ignorantia caecos et gravissimo facinore constrictos, zelum Dei Apostolus habere profitetur. Stephanus, qui per successionem cathedram Petri habere se praedicat, nullo adversus haereticos zelo excitatur, concedens illis non modicam sed maximam gratiae potestatem, ut dicat eos et asseveret per baptismi sacramentum sordes veteris hominis abluere, antiqua mortis peccata donare, regenaratione coelesti filios Dei facere, ad aeternam vitam divini lavacri sanctificatione reparare. Qui sic magna et coelestia Ecclesiae munera haereticis concedit et tribuit, quid aliud agit quam communicat eis quibus tantum gratiae defendit ac vindicat. Et frustra jam dubitat in caeteris quoque consentire eis et particeps esse, ut et simul cum eis conveniat, et orationes pariter cum iisdem misceat, et altare ac sacrificium commune constituat.