9Nicodemus said to him, “How can these things be?” 10Jesus answered him, “Are you the teacher of Israel and yet you do not understand these things? 11Truly, truly, I say to you, we speak of what we know, and bear witness to what we have seen, but you do not receive our testimony. 12If I have told you earthly things and you do not believe, how can you believe if I tell you heavenly things? 13No one has ascended into heaven except he who descended from heaven, the Son of Man. 14And as Moses lifted up the serpent in the wilderness, so must the Son of Man be lifted up, 15that whoever believes in him may have eternal life.
Nicodemus was a highly a respected teacher of the Old Testament Scriptures. So, he fully understood Jesus’ reference to this particular episode in Israel’s history.
During their Exodus from Egypt, when the Israelites were afflicted by poisonous snakes, “Moses made a bronze serpent and set it on a pole. And if a serpent bit anyone, he would look at the bronze serpent and live” (Numbers 21:9).
Of course, Jesus had His own future crucifixion in mind.
“lifted up” [huphoō]: (1) to lift up spatially, lift up, raise high; (2) to cause enhancement in honor, fame, position, power, or fortune, exalt.
William Arndt, Frederick W. Danker, and Walter Bauer,