79 Also another Januarius of Muzuli said: "I wonder that, while all acknowledge that there is one baptism, all do not understand the unity of the same baptism. For the Church and heresy are two distinct things. If heretics have baptism we have it not; but if we have it, heretics cannot have it. But there is no doubt that the Church alone possesses the baptism of Christ, since it alone possesses both the favor and the truth of Christ."
80. Another might equally say, and say with equal want of truth: I wonder that, while all confess there is one baptism, all do not understand the unity of baptism. For righteousness and unrighteousness are two distinct things. If the unrighteous have baptism, the righteous have it not; but if the righteous have it, the unrighteous cannot have it. But there is no doubt that the righteous alone possess the baptism of Christ, since they alone possess both the favor and the truth of Christ. This is certainly false, as they confess themselves. For those envious ones also who are of the party of the devil, though placed within the Church, as Cyprian tells us, and who were well known to the Apostle Paul, had baptism, but did not belong to the members of that dove which is safely sheltered on the rock.
Source: On Baptism, Against the Donatists (New Advent)