Cyprian of Carthage, On the Unity of the Church 14
Even if such people are killed confessing the name, that stain is not washed away by blood; the inexpiable and grave fault of discord is not purified by suffering. (1 Cor 13:2–3) No one who is not in the Church can be a martyr, and no one who abandons the Church, which is destined to reign, can arrive at the kingdom. Christ gave us peace, commanded us to be harmonious and of one mind, and ordered that the covenant of love and charity be kept incorrupt and inviolate. Anyone who did not hold fast to brotherly charity cannot present himself as a martyr. The apostle Paul teaches and testifies to this when he says: if I have faith so as to move mountains but do not have charity, I am nothing; and if I give away all my goods to feed the poor, and if I hand over my body to be burned, but do not have charity, I gain nothing. (1 Cor 13:2–3) Charity is magnanimous, charity is kind; charity does not envy, does not act shamefully, is not puffed up, is not provoked, does not count up wrongs; it bears all things, believes all things, hopes all things, endures all things. Charity never fails. Never, he says, does charity fail. For it will always remain in the kingdom; it will endure forever in the unbroken unity of brotherly concord. (1 Cor 13:4–8) Discord cannot enter the kingdom of heaven; the one who violates Christ's love with perfidious division cannot share in the rewards of Christ, who said, "This is my commandment, that you love one another, just as I have loved you." (John 13:34) Whoever lacks charity lacks God. The voice of the blessed apostle John declares: "God is love, and whoever remains in love remains in God, and God remains in him." (1 John 4:16) Those who refused to live in harmony in the Church of God cannot remain with God. Even if they are delivered to flames and fire, or thrown to the beasts and lay down their lives, the result will not be the crown of faith but the punishment of faithlessness; not the glorious outcome of religious virtue but the destruction of despair. Such a person can be killed, but cannot be crowned. Thus someone professes to be a Christian just as the devil often lies, claiming to be Christ himself, despite the Lord's own warning: "Many will come in my name, saying, 'I am the Christ,' and they will deceive many." (Matt 24:5) Just as that one is not the Christ though he deceives in the name, so also the one who does not remain in the truth of his Gospel and faith cannot be recognized as a Christian.
Latin
Tales etiamsi occisi in confessione nominis fuerint, macula ista nec sanguine abluitur: inexpiabilis et gravis culpa discordiae nec passione purgatur. Esse martyr non potest qui in Ecclesia non est: ad regnum pervenire non poterit qui eam quae regnatura est derelinquit. Pacem nobis Christus dedit, concordes atque unanimes esse praecepit, dilectionis et charitatis foedera incorrupta atque inviolata servari mandavit. Exhibere se non potest martyrem qui fraternam non tenuit charitatem. Docet hoc et contestatur Paulus apostolus dicens: Et si habuero fidem ita ut montes transferam, charitatem autem non habeam, nihil sum. Et si in cibos pauperum distribuero omnia mea, et si tradidero corpus meum ut ardeam, charitatem autem non habeam, nihil proficio. Charitas magnanima est, charitas benigna est, charitas non aemulatur, non agit perperam, non inflatur, non irritatur, non cogitat malum, omnia diligit, omnia credit, omnia sperat, omnia sustinet. Charitas numquam excidit. Numquam, inquit, excidit charitas. Haec enim semper in regno erit, haec in aeternum fraternitatis sibi cohaerentis unitate durabit. Ad regnum coelorum non potest pervenire discordia; ad praemia Christi, qui dixit, Hoc est mandatum meum, ut diligatis invicem, quemadmodum dilexi vos, pertinere non poterit qui dilectionem Christi perfida dissensione violavit. Qui charitatem non habet, Deum non habet. Joannis beati apostoli vox est: Deus, inquit, dilectio est; et qui manet in dilectione, in Deo manet, et Deus in illo manet. Cum Deo manere non possunt qui esse in Ecclesia Dei unanimes noluerunt. Ardeant licet flammis et ignibus traditi vel objecti bestiis animas suas ponant, non erit illa fidei corona, sed poena perfidiae; nec religiosae virtutis exitus gloriosus, sed desperationis interitus. Occidi talis potest, coronari non potest. Sic se christianum esse profitetur quomodo et Christum diabolus saepe mentitur, ipso Domino praemonente et dicente: Multi venient in nomine meo dicentes: Ego sum Christus, et multos fallent. Sicut ille Christus non est, quamvis fallat in nomine, ita nec christianus videri potest qui non permanet in Evangelii ejus et fidei veritate.