20 Besides, how vain and perverse a thing it is, that when the heretics themselves, having repudiated and forsaken either the error or the wickedness in which they had previously been, acknowledge the truth of the Church, we should mutilate the rights and sacrament of that same truth, and say to those who come to us and repent, that they had obtained remission of sins when they confess that they have sinned, and are for that reason come to seek the pardon of the Church! Wherefore, dearest brother, we ought both firmly to maintain the faith and truth of the Catholic Church, and to teach, and by all the evangelical and precepts to set forth, the plan of the divine dispensation and unity.
Source: The Epistles of Cyprian (New Advent)