Born of water

3 Now there was a man of the Pharisees named Nicodemus, a ruler of the Jews. 2 This man came to Jesus by night and said to him, “Rabbi, we know that you are a teacher come from God, for no one can do these signs that you do unless God is with him.” 3 Jesus answered him, “Truly, truly, I say to you, unless one is born again he cannot see the kingdom of God.” 4 Nicodemus said to him, “How can a man be born when he is old? Can he enter a second time into his mother's womb and be born?” 5 Jesus answered, “Truly, truly, I say to you, unless one is born of water and the Spirit, he cannot enter the kingdom of God. 6 That which is born of the flesh is flesh, and that which is born of the Spirit is spirit. 7 Do not marvel that I said to you, ‘You must be born again.’ 8 The wind blows where it wishes, and you hear its sound, but you do not know where it comes from or where it goes. So it is with everyone who is born of the Spirit.”

9 Nicodemus said to him, “How can these things be?” 10 Jesus answered him, “Are you the teacher of Israel and yet you do not understand these things? 11 Truly, truly, I say to you, we speak of what we know, and bear witness to what we have seen, but you do not receive our testimony. 12 If I have told you earthly things and you do not believe, how can you believe if I tell you heavenly things? 13 No one has ascended into heaven except he who descended from heaven, the Son of Man. 14 And as Moses lifted up the serpent in the wilderness, so must the Son of Man be lifted up, 15 that whoever believes in him may have eternal life (Jn 3:1-15).

This is a classic prooftext for baptismal regeneration. 

1. One stock objection is that a baptismal referent is out of context. The institution of Christian baptism lay in the future. Nicodemus is reprimanded for failing to grasp what Jesus is alluding to. But if it refers to baptism, he'd be in no position to discern it. That information is not yet available.  

Some theologians and commentators don't have a problem with the anachronism because they think this is a fictional dialogue that provides a backstory for later theological developments. But for Christians who affirm the historicity of the account, the anachronism can't be dismissed.

There are, however, other objections:

2. Jesus stresses the independence of the Spirit. Like wind, the Spirit is unpredictable. Wind can abruptly change direction. 

If, however, baptisml regeneration is true, then the Spirit's agency is regularly channeled through the sacrament of baptism. In that event, the theology of baptismal regeneration is diametrically opposed to Christ's comparison.

3. Moreover, proponents of baptismal regeneration typically believe two additional things:

i) Baptism is unrepeatable.

ii) A Christian can lose saving grace. He can pass from a state of grace to a state of mortal sin.

But if (ii) is true, then it's unclear why baptism is unrepeatable. If sacramental grace is resistible and amissible, then why wouldn't baptism be repeatable to restore what was lost? 

It's said that baptism confers an indelible mark on the soul, but that's in tension with the claim that sacramental grace is resistible and amissible.  Can the grace of baptism be lost or not? Trying to split the difference is gimmicky.