John 3:14, “As Moses lifted up the serpent in the wilderness, even so must the Son of Man be lifted up.” We have this third image here of the serpent on the pole. You recall when the people were in rebellion in the wilderness, God sent serpents to bite them and it would lead to death unless they looked to the brass serpent that Moses was instructed to build and put up.
The reason why He came to do such a radical thing was to make it possible for us to escape the wrath of God and to embrace instead the love of God. The One who deserves the love of God, namely the Son, receives the wrath of God on the cross.
The rest of this gospel will illustrate the truth of John 2:25. This is very, very clear in the dialogue with Nicodemus and also it goes on to be clear in the dialogue with the woman at the well in John 4.
Jesus is saying that the Spirit of God cannot just brush away sin when He grants the new birth. For sin to be dealt with, God’s justice must be satisfied. The Son of Man must be lifted up to satisfy God’s wrath on behalf of sinners who believe in Him.