10 And what have we done, say they? We are the persecuted, not the persecutors. You are the persecutors, O wretched men. In the first place, in that you have divided the Church. Mightier the sword of the tongue than the sword of steel. Agar, Sarah's maid, was proud, and she was afflicted by her mistress for her pride. That was discipline, not punishment. Accordingly, when she had gone away from her mistress, what said the angel to her? “Return to your mistress.” Then, O carnal soul, like a proud bond-woman, suppose you have suffered any trouble for discipline' sake, why do you rave?
“Return to your mistress,” hold fast the peace of the Church. Lo, the gospels are pro duced, we read where the Church is spread abroad: men dispute against us, and say to us, “Betrayers!” Betrayers of what? Christ commends to us His Church, and you believe not: shall I believe you, when you revile my parents? Would you that I should believe you about the “betrayers”? First believe Christ. What is worth believing? Christ is God, you are man: which ought to be believed first? Christ has spread His Church abroad over all the earth: I say it— despise me: the gospel speaks— beware.
What says the gospel? “It behooved Christ to suffer, and to rise again from the dead on the third day, and that repentance and remission of sins should be preached in His name.” Where remission of sins, there the Church is. How the Church? Why, to her it was said, “To you I will give the keys of the kingdom of heaven, and whatsoever you shall loose on earth shall be loosed in heaven, and whatsoever you shall bind on earth shall be bound in heaven.” Where is this remission of sins spread abroad?
“Through all nations, beginning at Jerusalem.” Lo, believe Christ! But, because you are well aware that if you shall believe Christ, you will not have anything to say about “betrayers,” you will needs have me to believe you when you speak evil against my parents, rather than yourself believe what Christ foretold!
Source: Homilies on the First Epistle of John (New Advent)