Normally I post the text of the passage in the post, but this passage is a little long so I will just link to it, here.
Nicodemus comes to visit Jesus at night. It is hard to say if this was to keep the visit a secret. It may have been. Certainly, as Moloney suggests, it represents movement by Nicodemus from darkness into the light. He was one of those who was attracted to Jesus by his signs. Would it result in genuine faith? We have to wait until later in the narrative to find out, but in the meantime we can learn where true faith springs from.
What did Nicodemus want to ask Jesus? We'll never know, as Jesus cuts him off prior to asking anything. Jesus' response indicates that Nicodemus has misunderstood something. Something is inadequate in his statement in verse 2. What Nicodemus needs is a divine birth, a moral transformation where he shares in God's moral nature. Nicodemus is completely baffled. He thinks Jesus is demanding two births, a physical impossibility. Jesus continues by stressing that he's talking about a different kind of birth all-together, a spiritual birth. Only then can one enter the kingdom of God. God's eschatological salvation will only come to those who possess the Spirit. Jesus expresses his disappointment that one who knew the Scriptures so well could misunderstand him.
Verses 11-12 confirm that there is something inadequate about Nicodemus' faith at the moment. What he failed to understand is that Jesus alone (and presumably those filled with his Spirit) possessed true revelation from God. All encounters with God, whether they be those of Moses or of the various figures like Enoch in apocalyptic literature were qualitatively different than those of the pre-existent Messiah. This means that Jesus alone is authoritative. But the sign of his authority is not what one would expect. His sign will be being placed on a sign, like the bronze serpent. Presumably the resulting salvation of those who place their trust in Jesus also will function as a sign.
Now we come to the most well known passage in the Bible. It was interesting studying it and seeing just how different the meaning is from how it is popularly conceived. If one were to read just verses 16-18 one would get the following picture. Jesus came because of God's love for the world. He did not desire to judge the world but to save it. All one has to do is trust Jesus and she or he will be saved. When we read the following three verses we find that the last sentence needs to be completely revised and we need to fill out the sentence prior a bit more, too. Jesus himself did not come to the world to condemn it. It already stood condemned. It stood condemned because the world was in darkness and was evil, except for a few. Those who were doing good deeds saw Jesus for who he was and had faith. Those who were doing evil rejected him confirming the condemnation that had already been declared. Thus, far from exalting faith alone, this passage fully integrates faith and works or perhaps better put - character - but works are given precedence over faith!
 This seems to me to be a sure place where editing happened, especially since the words of Jesus don't exactly respond to Nicodemus' earlier comment. They move the discussion onto another plane or dimension.
 The way misunderstanding is so heavily relied upon makes me think the NRSV rendering "born from above" is preferable to "born again," which is how Nicodemus understands Jesus. The Greek is ambiguous. Hebrew could not have been here, making it likely (unless Jesus and Nicodemus had this conversation in Greek which is unlikely but not impossible) that this narrative is the invention of the gospel writer (von Wahlde assigns this to the second stage of composition).
 Of course one presumes John has Ezekiel 36 in mind here and perhaps channeling that through Jeremiah 31:33-34.
 Though certainly he isn't really the target of this critique. It seems to be clearly aimed at those in the synagogue who had interest in Jesus but did not come to full faith.
 So, Michaels.
 So, Keener, whose comments here and elsewhere in this passage proved immensely helpful to me.
 A point Michaels makes clearly.