Justin Martyr, First Apology 61

I will explain how we devoted ourselves to God after being renewed through Christ, so that by covering this point we may not appear to be doing something wrong in our account. Those who are persuaded and believe that what we teach and say is true, and who promise they can live accordingly, are taught to pray and ask God for forgiveness of their past sins while fasting, with us praying and fasting alongside them. Then we lead them to where there is water, and they are reborn in the same manner of rebirth that we ourselves experienced. For in the name of God, the Father of all and our Master, and of our Savior Jesus Christ, and of the Holy Spirit, they undergo the washing in the water. Christ said, "Unless you are born again, you will not enter the kingdom of heaven" (John 3:5). It is obvious to everyone that those who have been born once cannot re-enter the wombs of those who gave birth to them. Through the prophet Isaiah, as we wrote earlier, it was declared how those who have sinned and repent will escape their sins. The words are: "Wash yourselves, become clean, remove the evil from your souls, learn to do good, seek justice for the orphan, defend the widow, and come now, let us reason together," says the Lord. "Though your sins are like scarlet, I will make them white as snow; though they are like crimson, I will make them white as wool. But if you refuse to listen, the sword will devour you, for the mouth of the Lord has spoken" (Isaiah 1:16–20). We learned this teaching from the apostles for this very reason. Since we were born by necessity from moist seed through the union of our parents, without knowledge of our first birth, and fell into foul and evil habits, we must not remain children of necessity and ignorance but become children of choice and knowledge, obtaining forgiveness for the sins we previously committed. Over the one who chooses to be reborn and has repented of their sins, the name of God, the Father of all and our Master, is invoked in the water as the one leading them to the washing pronounces that name alone. No one can utter a name for the unutterable God; anyone who dares claim to do so displays reckless madness. This washing is called enlightenment, because the minds of those learning these things are enlightened. And in the name of Jesus Christ, who was crucified under Pontius Pilate, and in the name of the Holy Spirit, who foretold through the prophets all things concerning Jesus, the one being enlightened is washed.