7 But if any one should ask what I hold in the meantime, while discussing this question, I answer that, in the first place, the letter of Cyprian suggested to me what I should hold till I should see clearly the nature of the question which next begins to be discussed. For Cyprian himself says: "But some will say, 'What then will become of those who in times past, coming to the Church from heresy, were admitted without baptism?'" Whether they were really without baptism, or whether they were admitted because those who admitted them conceived that they had partaken of baptism, is a matter for our future consideration. At any rate, Cyprian himself shows plainly enough what was the ordinary custom of the Church, when he says that in past time those who came to the Church from heresy were admitted without baptism.
8. For in the Council itself Castus of Sicca says: "He who, despising truth, presumes to follow custom, is either envious or evil-disposed towards the brethren to whom the truth is revealed, or is ungrateful towards God, by whose inspiration His Church is instructed." Whether the truth had been revealed, we shall investigate hereafter; at any rate, he acknowledges that the custom of the Church was different.
Source: On Baptism, Against the Donatists (New Advent)