What does John 4:23 mean?

This verse is crucial for two reasons. First, this is part of Jesus' correction on the meaning of worship. The Samaritan woman attempted to distract Jesus from her sin, by asking Him to resolve an old spiritual argument. This was the question of where proper worship should occur: Mount Gerizim or the temple of Jerusalem? Rather than taking the bait, Jesus clarifies that "true" worship of God is not tied to a location, but to the intent of one's heart.

This is also important for what it says about the Samaritan woman. She has lived a deeply immoral lifestyle (John 4:16–18), such that she seems to have been cast out, even among the outcast Samaritans. Nicodemus, the educated and powerful Pharisee, needed to be humbled in order to be opened to God (John 3:9–12). This woman needs to know that she is wanted, loved, and valued. As always, Jesus meets each person at the exact point of their need.

The Samaritan woman has been looking to quench her spiritual thirst with a series of failed relationships. At first she did not understand what Jesus meant by a spring of living water, leaving no more thirst (John 4:13–14). Based on what she says in the next verse, it seems to be dawning on her what Jesus is really speaking of.