And there went out unto him all the land of Judea, and they of Jerusalem, and were all baptized by him in the river Jordan, confessing their sins.
All Commentaries on Mark 1:5 Go To Mark 1
Jerome
AD 420
The baptism of John did not so much consist in the forgiveness of sins as in being a baptism of repentance for the remission of sins, that is, for a future remission, which was to follow through the sanctification of Christ.