63 Another Felix of Uthina said: "No one can doubt, most holy brethren in the priesthood, that human presumption has not so much power as the adorable and venerable majesty of our Lord Jesus Christ. Remembering then the danger, we ought not only to observe this ourselves, but to confirm it by our general consent, that all heretics who come to the bosom of our mother the Church be baptized, that the heretical mind, which has been polluted by long-continued corruption, may be reformed when cleansed by the sanctification of the laver."
64. Perhaps the man who has placed the strength of his case for the baptizing of heretics in the cleansing away of the long-continued corruption, would spare those who, having fallen headlong into some heresy, had remained in it a brief space, and presently being corrected, had passed from thence to the Catholic Church. Furthermore, he has himself failed to observe that it might be said that all unrighteous persons who come to that rock, in which is understood the Church, should be baptized, so that the unrighteous mind, which was building outside the rock upon the sand by hearing the words of Christ and not doing them, might be reformed when cleansed by the sanctification of the laver; and yet this is not done if they have been baptized already, even if it be proved that such was their character when they were baptized, that is, that they "renounced the world in words and not in deeds."
Source: On Baptism, Against the Donatists (New Advent)