You have to have some sympathy for Nicodemus. From all appearances, he was a person who wanted to do what was right. Although Jesus was not in favor with the leadership of Israel and Nicodemus was part of that group, he sought Jesus out (John 3) even though it meant putting him at odds with his peers.
Later, when John reports on Jesus’ visit to Jerusalem during the Feast of the Tabernacles, he tells us that the temple guards who had been sent to arrest Him came back empty-handed. They explanation they gave for their failure was that “No one ever spoke the way this man does” (7:46). They were ridiculed by the leadership who told them they had been deceived. At this point Nicodemus spoke up and posed a point of Jewish law very similar to our “innocent until proven guilty” principle in regard to Jesus. But he was also mocked. Admittedly, these are glimpses, but I think they are revealing glimpses that provide us with insight into Nicodemus’ character and present him to us as a conscientious person.
When we return to Nicodemus’ nighttime visit with Jesus in John 3 it all adds up. Here was a truth-seeking man unable to discount the signs (miracles) Jesus had been doing. He knew his peers didn’t look favorably on Jesus and was conflicted by that. However, if he thought his visit with Jesus would resolve this, he was about to be surprised for as someone has said, “The truth will set you free, but first it will make you miserable.”
When Nicodemus met with Jesus, he had quite an impressive resume. He was a Pharisee, a member of the Sanhedrin, a leader of his people. As a Jewish man he was part of God’s covenant people. In terms of his fleshly status which was legitimately part of the old covenant and illegitimately blown out of proportion by so many of the Jewish people of Jesus’ time—he was an insider with all of the attendant privileges. So I think we’re to get the idea that he felt pretty secure in his standing before God and fairly confident of his potential value to the kingdom Jesus was preaching (Mark 1:14-15).
All of this sets us the stage for Jesus’ startling proclamation that Nicodemus needed to be born again (from above) in order to see the kingdom of God (John 3:5). Nicodemus is shocked—he had experienced the fleshly birth that brought him into the Jewish covenant but in the kingdom of Jesus it is the birth of the Spirit, not the flesh, that marks us as children of God (John 1:12-13). Nicodemus then is lost in the transition between the time of Israel and the time of Christ. But there’s more to the story concerning why Jesus told him he needed to be born of the water and Spirit than simply that . . .