“I do not pray for these alone, but also for those who will believe in Me through their word; that they all may be one, as You, Father, are in Me, and I in You; that they also may be one in Us, that the world may believe that You sent Me. And the glory which You gave Me I have given them, that they may be one just as We are one: I in them, and You in Me; that they may be made perfect in one, and that the world may know that You have sent Me, and have loved them as You have loved Me.” (John 17:20-23)
“But a common faith was not the sole mark of unity; mutual love was its other and perhaps even more crucial indicator. Cyprian quotes 1 Corinthians 13:8 (“Love never ends…”) and declares:
It will exist forever in the kingdom, it will endure forever in the union of the brethren among themselves. Disunion cannot attain to the kingdom of heaven, nor can one who has violated the love of Christ by wicked dissension win the reward of Christ, who said, “This is my commandment, that you love one another as I have loved you” [John 15:12].”
Thus schism, the fracturing of ecclesial unity, is almost always characterized as a breach of love; and as love is the greatest of virtues, so schism is the worst of the vices. At the root of schism is that pride and self-righteousness that allowed some individuals to make extravagant claims to holiness for themselves. Where do schisms come from? Augustine asks–and then answers the question: “When people say, ‘We are righteous’; when they say, ‘We sanctify the unclean, we justify the impious, we make petition, we obtain [what we ask for].’”
Ecclesial unity was not something to be cherished merely for its own sake, however. Its importance lay substantially in the fact that it mirrored the unity of the Godhead itself. “God is one,” writes Cyprian, “and Christ is one, and his Church is one, and there is one faith and one people joined together by harmony into the strong unity of a body.” Despite Cyprian’s emphasis on the idea of the Church as the reflection of God’s unity, the theme is even more evident in the letters of Ignatius of Antioch, who preceded Cyprian by nearly a century and a half. The concord of its members, of its people and its ministers, images the unity of the Father and the Son.
‘Just as the Lord, then, being one with himself did nothing without the Father, either by himself or through the apostles, so neither must you do anything without the bishop and the presbyters. And you must not attempt to convince yourselves that anything you do on your own account is right, but there must be in common, one prayer, one supplication, one mind, one hope in love, in flawless joy, that is Jesus Christ, than whom nothing is better. Come together, all of you, as to one temple of God, as to one altar, to one Jesus Christ, who came forth from one Father and yet remained with one and returned to one.'”
(Boniface Ramsey, Beginning to Read the Fathers, pp.104-105)