We have just seen the conversation between Son of God and one of the great teachers of his day (John 3:1-21). Nicodemus was a highly respected teacher and one of the Jewish rulers in the Sanhedrin. Nicodemus thought he knew a lot about God, and yet Jesus showed him that he needed to be born from above before he could even see God’s kingdom (see here).
The next scene is a complete contrast to Nicodemus. Jesus initiates a conversation with an outcast Samaritan woman, one who would be despised by any “respectable” Jew. Nicodemus had initiated a secret meeting with Jesus for fear of reprisal from his own countrymen. Jesus initiates this next meeting with an immoral “foreigner” woman with no fear of reprisal.
Jesus’ message to Nicodemus was that the spiritual world is much greater than anything we can see or hear. Jesus further explains the spiritual world to this sinful, Samaritan woman using water.
The Samaritan woman would not have understood the Old Testament metaphor of water’s cleansing and new life . But more importantly, Jesus is bringing her to the point of understanding eternal life. The well water is temporary, but Jesus is offering something permanent.
Jesus then brings her to the next step, which is to show her that he knows about the details of her life. He knows all about her five failed marriages and that she is not married to her current man. Note that Jesus neither excuses nor corrects her current lifestyle. What is most important is that she needs eternal life.
The woman’s response seems strange to our minds. She almost seems to change the subject, asking about the place of worship. But her core Samaritan beliefs had been shaken. The Samaritans did not believe in any other prophet after Moses except for the Messiah . Therefore, she has just acknowledged that this man must be be the Messiah. And he is a Jew. Therefore, what else about her Samaritan beliefs were wrong?
The Samaritans believed that the the true source of worship was on Mount Gerizim (see here). If the rest of her Samaritan beliefs were wrong, where was the correct place to worship? More specifically, how can you come to God?
How do you worship God? Jesus says it twice here: You worship God in spirit and truth.
You worship God in spirit. This is not a reference to the Holy Spirit but in the human spirit, the part of us that communes with God. As we draw close to God, our worship of God comes from the inside-out. 
You worship God in truth. It is not enough to have great emotions, or to feel close to God. Our worship of God is rooted in the truth of knowing who he is and in studying his Word.
The woman points out that truth will come from the Messiah. Jesus unmistakably declares that he is the Messiah.
It is this faith in Jesus that brings her to eternal life:
“The conviction, sudden but firm, that He Who had laid open the past to her was really a Prophet, was already faith in Him; and so the goal had been attained – not, perhaps, faith in His Messiahship, about which she might have only very vague notions, but in Him. And faith in the Christ, not in anything about Him, but in Himself, has eternal life.” – Alfred Edersheim 
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