What does John 4:21 mean?

Jesus is responding to the Samaritan woman's attempted distraction. Often, in evangelism or debate, one side will try to lure the other into a discussion not relevant to the point at hand. This usually comes in an effort to avoid the original topic. In this case, Jesus has just confronted the woman about her immoral lifestyle (John 4:17–18). Her clever-minded response is to ask Jesus about a controversial spiritual question (John 4:19–20).

Instead of taking the bait, Jesus simply deflects the question. The issue is simply not important as part of the conversation they are having. Instead of chasing a false trail, Jesus continues to explain the gospel. The woman's question revolves around the proper location for worship. Jews only worshipped in the temple. Samarians only worshipped on Mount Gerizim. Jesus explains that, once His mission is complete, that worship will not be confined to any one place on earth. This would have been just as controversial to the Jews, who placed great importance in the physical temple.

This leads Jesus into an important truth about proper Christian worship: it requires spirit and truth.