1 Cyprian to Epictetus his brother, and to the people established at Assurae, greeting. I was gravely and grievously disturbed, dearest brethren, at learning that Fortunatianus, formerly bishop among you, after the sad lapse of his fall, was now wishing to act as if he were sound, and beginning to claim for himself the episcopate. Which thing distressed me; in the first place, on his own account, who, wretched man that he is, being either wholly blinded in the darkness of the devil, or deceived by the sacrilegious persuasion of certain persons; when he ought to be making atonement, and to give himself to the work of entreating the Lord night and day, by tears, and supplications, and prayers, dares still to claim to himself the priesthood which he has betrayed, as if it were right, from the altars of the devil, to approach to the altar of God.
Or as if he would not provoke a greater wrath and indignation of the Lord against himself in the day of judgment, who, not being able to be a guide to the brethren in faith and virtue, stands forth as a teacher in perfidy, in boldness, and in temerity; and he who has not taught the brethren to stand bravely in the battle, teaches those who are conquered and prostrate not even to ask for pardon; although the Lord says, “To them have you poured a drink-offering, and to them have you offered a meat-offering.
Shall I not be angry for these things? Says the Lord.” And in another place, “He that sacrifices to any god, save unto the Lord only, shall be destroyed.” Moreover, the Lord again speaks, and says, “They have worshipped those whom their own fingers have made: and the mean man bows down, and the great man humbles himself: and I will not forgive them.” In the Apocalypse also, we read the anger of the Lord threatening, and saying, “If any man worship the beast and his image, and receive his mark in his forehead or in his hand, the same shall drink of the wine of the wrath of God mixed in the cup of His anger; and he shall be tormented with fire and brimstone in the presence of the holy angels, and in the presence of the Lamb: and the smoke of their torments shall ascend up for ever and ever; neither shall they have rest day nor night, who worship the beast and his image.”
Source: The Epistles of Cyprian (New Advent)