Justin Martyr on Baptism in 160CE

So that you will fully understand everything there is to know about us, I want to describe the manner in which we dedicate ourselves to God when we have been made new through Christ.  First, those persons who are convinced that what we teach is true, and who promise that they can live accordingly, are instructed to implore God with prayer and fasting for the forgiveness of all past sins.  We pray and fast with them. 

Then we take them to a place where there is water, and they are spiritually reborn in the same manner in which we ourselves were reborn.  Then they are washed with the water in the name of God, the Father and Lord of the universe, and of our Savior Jesus Christ, and of the Holy Spirit.  For Christ said, “Unless you are born again, you will not enter the kingdom of heaven.”

Of course, it is obvious that it’s impossible for a person who has already been born to re-enter his mother’s womb.  Rather, Isaiah the prophet explained how those who have sinned, but are repentant, can escape their sins: “‘Wash and be clean.  Put all evil away from your souls.  Learn to do what is right.  Help the fatherless and plead for the widow.  And come and let us reason together,’ says the Lord. ‘And though your sins may be as scarlet, I will make them white as wool. Though they may be crimson, I will make them white as snow.’”

The apostles taught us the reason for this ceremony, as follows.  We have no say in our original birth.  It results from the union of our parents.  And often we grow up ignorant of the truth, being raised in bad habits and being taught wicked things. 

However, we do not have to remain the children of necessity and ignorance.  We can become the children of choice and knowledge through a second birth.  In order for a person to obtain the forgiveness of his past sins in the water, there is pronounced over him – the one choosing to be born again and who has repented of sins – the name of God, the Father and Lord of the universe. … And the person … is washed also in the name of Jesus Christ, who was crucified under Pontius Pilate, and in the name of the Holy Spirit.