54 Another Saturninus of Abitini said: "If Antichrist can give to any one the grace of Christ, then can heretics also baptize, who are called Antichrists."
55. What if another were to say, If a murderer can give the grace of Christ, then can they also baptize that hate their brethren who are called murderers? For certainly he would seem in a way to speak the truth, and yet they can baptize; in like manner, therefore, can the heretics as well.
Source: On Baptism, Against the Donatists (New Advent)