2 Wherefore it behooves you to write a very copious letter to our fellow bishops appointed in Gaul, not to suffer any longer that Marcian, froward and haughty, and hostile to the divine mercy and to the salvation of the brotherhood, should insult our assembly, because he does not yet seem to be excommunicated by us; in that he now for a long time boasts and announces that, adhering to Novatian, and following his frowardness, he has separated himself from our communion; although Novatian himself, whom he follows, has formerly been excommunicated, and judged an enemy to the Church; and when he sent ambassadors to us into Africa, asking to be received into our communion, he received back word from a council of several priests who were here present, that he himself had excluded himself, and could not by any of us be received into communion, as he had attempted to erect a profane altar, and to set up an adulterous throne, and to offer sacrilegious sacrifices opposed to the true priest; while the Bishop Cornelius was ordained in the Catholic Church by the judgment of God, and by the suffrages of the clergy and people. Therefore, if he were willing to return to a right mind, and to come to himself, he should repent and return to the Church as a suppliant. How vain it is, dearest brother, when Novatian has lately been repulsed and rejected, and excommunicated by God's priests throughout the whole world, for us still to suffer his flatterers now to jest with us, and to judge of the majesty and dignity of the Church!
Source: The Epistles of Cyprian (New Advent)