We enter John 4, but not before we hear John  the Baptizers (remember this is not John the writer-of-this-book) testimony of who Jesus is… it clarifies what the conversation between Nicodemus and Jesus was about:

“”The one who comes from above is above all; the one who is from the earth belongs to the earth, and speaks as one from the earth. The one who comes from heaven is above all. He testifies to what he has seen and heard, but no one accepts his testimony. The man who has accepted it has certified that God is truthful. For the one whom God has sent speaks the words of God, for God gives the Spirit without limit. The Father loves the Son and has placed everything in his hands. Whoever believes in the Son has eternal life, but whoever rejects the Son will not see life, for God’s wrath remains on him.”” (John 3:31-36, NIV)