4 And therefore you have acted advisedly and with vigour, dearest brother, in excommunicating the deacon who has often abode with a virgin; and, moreover, the others who had been used to sleep with virgins. But if they have repented of this their unlawful lying together, and have mutually withdrawn from one another, let the virgins meantime be carefully inspected by midwives; and if they should be found virgins, let them be received to communion, and admitted to the Church; yet with this threatening, that if subsequently they should return to the same men, or if they should dwell together with the same men in one house or under the same roof, they should be ejected with a severer censure, nor should such be afterwards easily received into the Church.
But if any one of them be found to be corrupted, let her abundantly repent, because she who has been guilty of this crime is an adulteress, not (indeed) against a husband, but against Christ; and therefore, a due time being appointed, let her afterwards, when confession has been made, return to the Church. But if they obstinately persevere, and do not mutually separate themselves, let them know that, with this their immodest obstinacy, they can never be admitted by us into the Church, lest they should begin to set an example to others to go to ruin by their crimes.
Nor let them think that the way of life or of salvation is still open to them, if they have refused to obey the bishops and priests, since in Deuteronomy the Lord God says, “And the man that will do presumptuously, and will not hearken unto the priest or judge, whosoever be shall be in those days, that man shall die, and all the people shall hear and fear, and do no more presumptuously.” God commanded those who did not obey His priests to be slain, and those who did not hearken to His judges who were appointed for the time.
And then indeed they were slain with the sword, when the circumcision of the flesh was yet in force; but now that circumcision has begun to be of the spirit among God's faithful servants, the proud and contumacious are slain with the sword of the Spirit, in that they are cast out of the Church. For they cannot live out of it, since the house of God is one, and there can be no salvation to any except in the Church. But the divine Scripture testifies that the undisciplined perish, because they do not listen to, nor obey wholesome precepts; for it says, “An undisciplined man loves not him that corrects him. But they who hate reproof shall be consumed with disgrace.”
Source: The Epistles of Cyprian (New Advent)