Nicodemus, a ruler of Jerusalem, nevertheless had to come to Him under the cover of darkness. (John 3:1-21)
"Truly, truly, I say to you unless one is born anew, he cannot see the kingdom of God." This teacher of Israel had never heard of such a thing. How can a man come out of his mother's womb a second time?
Jesus makes it clear he is talking about a different kind of birth -- one accomplished with water and the spirit. In the Prologue of the Gospel, John makes it clear that all who received Christ were given this Baptism: the power to become children of God, children "who were born, not of blood nor the will of the flesh, nor of the will of man, but of God." (Jn 1:13) Baptism is new birth into a special relationship with God!
Nicodemus wants to know how this can be. Jesus answers by telling him He is God made man: "No one has ascended into heaven but he who descended from heaven, the Son of Man." Then He added that just as Moses took the poison of the serpent's bite from the people when he held up an image of the serpent in the desert, so the Son of Man shall remove the poison of sin when He is lifted up on the cross: "And as Moses lifted up the serpent in the wilderness, so will the Son of man be lifted up that whoever believes in him may have have eternal life." (Jn 3:14)
What a power packed interview. Christ meets the man who will someday help prepare his body for burial, introduces him to Baptism, explains this is accomplished through the Passion and Death of Jesus Christ, True God and True Man. "For God so loved the world that He gave His only Son, that whoever believes in Him should not perish, but have eternal life." (Jn 3:16) And the Word was made flesh and dwelt among us. (Jn 1:14)