1.There was a man of the Pharisees named Nicodemus, a ruler of the Jews. 2. This man came to Jesus by night and said to Him, “Rabbi, we know that You are a teacher come from God; for no one can do these signs that You do unless God is with him.”
3. Jesus answered and said to him, “Most assuredly, I say to you, unless one is born again, he cannot see the kingdom of God.”
4. Nicodemus said to Him, “How can a man be born when he is old? Can he enter a second time into his mother’s womb and be born?”
5. Jesus answered, “Most assuredly, I say to you, unless one is born of water and the Spirit, he cannot enter the kingdom of God.
Matt-in-the-Hat 
“Rabbi, we know that You are a teacher…”
A lot of people don’t realize that Jesus was a Jew. He would have self-identified as a Jew trying to reform the Judaism of his day and his followers would have identified as Jews. The Last Supper was actually the Last Seder, moved up a bit because he knew all about his impending crucifixion. Christianity as a separate faith would not have emerged until after his death. We can probably credit St Paul for that.
Just my take on it.