2 They maintain that those who have attained to perfect knowledge must of necessity be regenerated into that power which is above all. For it is otherwise impossible to find admittance within the Pleroma, since this [regeneration] it is which leads them down into the depths of Bythus. For the baptism instituted by the visible Jesus was for the remission of sins, but the redemption brought in by that Christ who descended upon Him, was for perfection; and they allege that the former is animal, but the latter spiritual.
And the baptism of John was proclaimed with a view to repentance, but the redemption by Jesus was brought in for the sake of perfection. And to this He refers when He says, “And I have another baptism to be baptized with, and I hasten eagerly towards it.” Moreover, they affirm that the Lord added this redemption to the sons of Zebedee, when their mother asked that they might sit, the one on His right hand, and the other on His left, in His kingdom, saying, “Can you be baptized with the baptism which I shall be baptized with?” Paul, too, they declare, has often set forth, in express terms, the redemption which is in Christ Jesus; and this was the same which is handed down by them in so varied and discordant forms.
Source: Adversus haereses (New Advent)