We then lead them [catechumens] to a place where there is water and they are reborn in the same way as we were reborn; that is to say, they are washed in the water in the name of God, the Father and Lord of the whole universe, of our Savior Jesus Christ and of the Holy Spirit. This is done because Christ said: “Unless you are born again you will not enter the kingdom of heaven,” and it is obviously impossible for anyone, having once been born, to re-enter their mother’s womb.
An explanation of how repentant sinners are to be freed from their sins is given through the prophet Isaiah in the words: “Wash yourselves and be clean. Remove the evil from your souls; learn to do what is right. Be just to the orphan, vindicate the widow. Come, let us reason together, says the Lord. If your sins are like scarlet, I will make them white as wool; if they are like crimson, I will make them white as snow. But if you do not heed me, you shall be devoured by the sword. The mouth of the Lord has spoken.”