12 I ask, therefore, if sins were remitted by the baptism of John, what more could the baptism of Christ confer on those whom the Apostle Paul desired to be baptized with the baptism of Christ after they had received the baptism of John? But if sins were not remitted by the baptism of John, were those men in the days of Cyprian better than John, of whom he says himself that they "used to seize on estates by treacherous frauds, and increase their gains by accumulated usuries," through whose, administration of baptism the remission of sins was yet conferred?
Or was it because they were contained within the unity of the Church? What then? Was John not contained within that unity, the friend of the Bridegroom, the preparer of the way of the Lord, the baptizer of the Lord Himself? Who will be mad enough to assert this? Wherefore, although my belief is that John so baptized with the water of repentance for the remission of sins, that those who were baptized by him received the expectation of the remission of their sins, the actual remission taking place in the baptism of the Lord,— just as the resurrection which is expected at the last day is fulfilled in hope in us, as the apostle says, that "He has raised us up together, and made us sit together in heavenly places in Christ Jesus;" and again, "For we are saved by hope;" or as again John himself, while he says, "I indeed baptize you with water unto repentance, for the remission of your sins," yet says, on seeing our Lord, "Behold the Lamb of God, which takes away the sin of the world," — nevertheless I am not disposed to contend vehemently against any one who maintains that sins were remitted even in the baptism of John, but that some fuller sanctification was conferred by the baptism of Christ on those whom Paul ordered to be baptized anew.
Source: On Baptism, Against the Donatists (New Advent)