Just as Jesus marveled that a smart fellow doesn’t understand (John 3:10).
The problem (John 3:11) is that, even though he is hearing our reliable testimony, Sonnet doesn’t “receive” the testimony. He is not yet (or may never be) among the number described in John 1:12— “But to all who did receive him, who believed in his name, he gave the right to become children of God.”
We have taken him as far as we can by way of explanation. He cannot go any higher. “If we have told you earthly things and you do not believe, how can you believe if we tell you heavenly things?” (John 3:12)
In effect, we, like Our Lord must say, “Sonnet, you keep pressing us for deeper and higher explanations of the new birth. But a heart of unbelief, an unregenerate heart, can’t ascend to the kinds of truth that we have to give you about the new birth.”
There are more obstacles to his entering the kingdom than merely his need to be born again. Something has to happen to remove the wrath of God so that he will release the power of the Spirit to cause Sonnet to be born again (see John 3:36). That’s what the Son of Man came to do (John 3:13).
Explaining what he came to do, Jesus picked an analogy, but it is shocking that he would pick it to describe his own work (John 3:14-15).
The shocking analogy used by Jesus relied upon the account of Moses who lifted up the serpent in the wilderness (Numbers 21:4–9); likewise must the Son of Man be lifted up, that whoever believes in him may have eternal life.
Jesus compares himself with a snake. Shocking.
- Note that the snake on the pole does not prevent anything at all. Rather it is for bitten people (Numbers 21:8). The poison is in them, and without divine intervention they will die.
- Also observe that the snakes in the camp are from the Lord. God sent them (Numbers 21:6). The wrath of God is on this people for their sin of ingratitude, murmuring, and rebellion.
- Further, we see that the means God chooses to rescue the people from his own curse is a picture [a type] of the curse itself.
- Now all the bitten ones have to do in order to be saved from God’s wrath is look at God's provision hanging on a pole. Now Moses is not being treated here as the rescuer, a savior. In Numbers, the one who saves is God by means of the snake. And in the Gospel of John, the one who saves is God by means of Jesus.
Of course we already know from Scripture's recording of Jesus' own words that he read the Old Testament believing that it was all pointing to him (John 5:39). There were types and foreshadows throughout the Old Testament. Jesus, in the place of the snake, is the source of healing, the source of rescue from the poison of sin and the wrath of God.
Yet observe that Jesus in the place of the snake is portrayed as evil and a curse. Shocking. The snake is evil. The snakes were killing people. The snake on the pole is a picture of God’s curse on the people. So it was with Jesus.
Paul writes in 2 Corinthians 5:2, “For our sake [God] made him to be sin who knew no sin, so that in him we might become the righteousness of God.” And in Galatians 3:13, Paul writes, “Christ redeemed us from the curse of the law by becoming a curse for us.” In becoming like the snake, Jesus was the embodiment of our sin, and the embodiment of our curse. And in becoming sin and curse for us, Jesus took ours away.
Jesus gives us eternal life via the cross. John 3:14-15: “The Son of Man must be lifted up, that whoever believes in him may have eternal life.”
All of this Jesus is saying to Nicodemus in John 3, yet Nicodemus (Sonnet) is very confused about the new birth and how it happens. The above is what you say to a person who is not born again. Why? They are dead and blind and God ordains to open the eyes of the blind when they have something to see—a compelling picture of Jesus crucified for sinners.
And what should you do, Nicodemus (Sonnet)? What should you do today?
Believe in him. John 3:15: “that whoever believes in him may have eternal life.” What does that mean? What does it involve? What, in this comparison with the snake on a pole, does believe in him mean? It means look to Jesus. The grace of the new birth is our seeing Christ lifted up. We behold his glory as he is lifted up, and in that look we receive grace.
Nicodemus (Sonnet), do you want the grace of the new birth? Look!
AMR
The spies being sent out to check out the land of Promise, is another example. Some claimed the men were so large that "we were.... like grasshoppers" to them. 
