NOTES for Joh 3:3-4
Among the Pharisees there were different people, and they related to Jesus in different ways. Among the spiritual leaders of the movement there were some who showed sincere interest in Him and in His words. Nicodemus was one of these people. He comes to Jesus with words of support and approval, calling Him a "true teacher." It is hard to say what meaning Nicodemus put into these words. It is entirely possible that he did not consider Jesus the Messiah. But Jesus Himself, as we see, is not going to discuss the question of His messiahship with Nicodemus.
In response to Nicodemus's assurances that he and those of like mind see in Jesus a true teacher, Jesus immediately speaks to him about a second birth. About birth from above. From water and God's breath. Usually people say: this is about baptism. Yes, it is clearly about baptism. But why, then, is Nicodemus so astonished? Those purifying washings that came to be called baptism were already long and well known to the Jews.
If this mysterious Teacher had merely proposed one more purifying washing, there would have been nothing unusual in that. But He speaks about a second birth, and Nicodemus does not understand Him. Though he should have: "Are you the teacher of Israel, and do you not know even this?" Jesus speaks of the second birth as something that could and should have been known to Nicodemus, if only he were a true teacher of Israel. And clearly the issue is not simply purifying washings. Still, Nicodemus speaks about the benefit of new birth as something self-evident but unattainable. He does not ask "Why?"; he says "How?" How can one be born a second time?
Why is clear: it is the most radical way to be freed from impurity. To begin life again. From a clean slate. And never again be defiled. But how? Jesus says: from water and God's breath. This sounds strange, because in those days it was commonly thought that God either purifies a person or sanctifies him. First He purifies, then He sanctifies. First purification, washing, and a sacrifice for sin, and then a sacrifice of peace. And perhaps then God's breath will descend upon a person. But purification and God's breath at once? Yet Jesus is speaking of the life of the Kingdom.
Of how accessible it is here and now, and in this sense His words are "about earthly things." About the breath of the Kingdom that purifies. And every time renews a person, as if bringing him to birth again: for in the Kingdom every day is new. And, of course, water: for until the full transformation of human nature there is no escaping sin. This is "about earthly things." And this is incomprehensible. As for "heavenly things," they are not yet even being discussed. They lie ahead. When the Kingdom is revealed in our fallen world to the end, fully transforming it. And there will no longer be any need for purifications. But that lies ahead. For now there are right steps. For now, "earthly things."