“Very truly, I tell you, we speak of what we know and testify to what we have seen; yet you do not receive our testimony. If I have told you about earthly things and you do not believe, how can you believe if I tell you about heavenly things? No one has ascended into heaven except the one who descended from heaven, the Son of Man. And just as Moses lifted up the serpent in the wilderness, so must the Son of Man be lifted up, that whoever believes in him may have eternal life.
“For God so loved the world that he gave his only Son, so that everyone who believes in him may not perish but may have eternal life.
"Indeed, God did not send the Son into the world to condemn the world, but in order that the world might be saved through him. Those who believe in him are not condemned; but those who do not believe are condemned already, because they have not believed in the name of the only Son of God. And this is the judgment, that the light has come into the world, and people loved darkness rather than light because their deeds were evil. For all who do evil hate the light and do not come to the light, so that their deeds may not be exposed. But those who do what is true come to the light, so that it may be clearly seen that their deeds have been done in God.” John 3:1-21
To some, it may seem that Jesus is giving a cryptic teaching but Jesus is trying to be as elemental as he can about the nature of God's Spirit.
Nicodemus meets Jesus under the cover of darkness probably to suss Jesus out. Many times, the religious teachers would start a conversation with Jesus with a compliment. But, Jesus knew the hearts of men and would typically respond with a test of a person's true understanding. In this case, Nicodemus says in part, "...we know that you are a teacher who has come from God..." Jesus answers, "Very truly, I tell you, no one can see the kingdom of God without being born from above." In other words, Jesus is answering Nicodemus' claim that they truly believe Jesus is from God and Jesus questions their understanding of what they are seeing. Nicodemus quickly reveals that he has no true understanding of Jesus nor the kingdom of God.
As Jesus explains later to his disciples, the key to understanding his teachings is a matter of perspective and humility. The perspective of the Pharisees is one that is typical of a quasi-ruling class who have some amount of power to lose when there is a threat to the current system. At this time, the religious teachers are seeing this one rabbi from the lowly town of Nazareth performing signs and miracles and amassing large crowds. This unknown, budding Jesus movement may threaten the people's respect for them as religious teachers and therefore their ability to control the people they rule over. The perception of losing control gives birth to fear. And fear is the seed of fearful actions (What is born of flesh is flesh, but what is born of spirit is spirit.) They must find out what Jesus' intentions are and more importantly if there is anything in it for them.
Nicodemus tries to find out and Jesus skilfully reveals this to be the case. Jesus' comparing the Spirit to the wind is quite telling. Nicodemus seems to know Jesus is at the least drawing his power from God. But he has difficulty fully accepting that reality because of certain assumptions he has made about God. He assumes God favours the Pharisees. Why would God be interested in sinners? Who Jesus is, where he comes from and how he has conducted his ministry so far seems to contradict those assumptions.
What is the reaction of Nicodemus to what is happening? "Awesome! God is working in our midst. O Lord, please tell us what you want us to do while you are here?" No. The reaction from Nicodemus and the religious teachers is, "Uh oh, there is something happening here and it seems to be from God. But I hope not because this may not bode well for us." (The wind blows where it chooses, and you hear the sound of it, but you do not know where it comes from or where it goes.) Instead of trusting God with their lives no matter where that takes them, they want to control their own destiny even if that means deceiving themselves into thinking they can control and manipulate who God is in the mind of their people.
Jesus then explains to Nicodemus that their lack of understanding and respect for God prevents them from believing who Jesus is and what Jesus' intentions are. They assume that God has no interest in sinners and desires to destroy and punish people. Jesus explains that this is not the case and that his very presence demonstrates that this is not the case. (For God so loved the world that he gave his only Son, so that everyone who believes in him may not perish but may have eternal life. Indeed, God did not send the Son into the world to condemn the world, but in order that the world might be saved through him.) Jesus came to save, not to condemn. Jesus came to give life not bring death. The Pharisees' stubborn hearts born out of pride in their own flesh and understanding did not allow them to acknowledge this. They refused to believe that Jesus was the Son of God.
Over the centuries, false religious teaching may change names and teachers, but the philosophy of denying who God has revealed himself to be the nation of Israel and through His Son Jesus remains the same. For example, "spiritual" guru Oprah Winfrey says during her New Earth seminars, "God is a feeling experience, not a believing experience." In other words, God is whoever you want Him to be as long as this works for what YOU want to accomplish in YOUR life. The teachings of the Bible and the teachings of Jesus clearly say again and again that this is simply not the case. To have an eternal and full life, each of us must believe that God is exactly who He says He is through His Son Jesus.
As we see later in the story, the Pharisees did not believe Jesus and this was demonstrated by their actions. They would only acknowledge Jesus as "a teacher who has come from God" at night, under the cover of darkness. And Jesus warns Nicodemus that this action demonstrates their state of being in God. (For all who do evil hate the light and do not come to the light, so that their deeds may not be exposed. But those who do what is true come to the light, so that it may be clearly seen that their deeds have been done in God.
They were so quick to do God's job for Him. They thought it was their job to determine who is saved and who is condemned. Who is God's favoured and who is God's cursed. Jesus warns Nicodemus that the Pharisees need to re-evaluate how they determine such things (Those who believe in him are not condemned; but those who do not believe are condemned already, because they have not believed in the name of the only Son of God.)