What does 1 Corinthians 12:16 mean?

This passage uses the illustration of the human body to show the importance of diverse Christians working together as a single church. It is irrational for a Christian to decide they don't want to be part of the church because they don't like what God has given them to do in their spiritual walk. Since the church is like a body, Paul says, the members of the body can't just decide to walk away. That's bad for the body, and worse for the missing piece!

Paul repeats the pattern of the previous verse: that a foot's claim not to belong to the body because it can't be a hand doesn't make sense. This time, though, it is the ear that complains that it is not an eye. If it can't be an eye, it decides it is not attached to the body, any longer. The problem, of course, is that it's still sitting there. It might choose not to function—and that's bad for the rest of the body. Parts of bodies could not quit even if they wanted to.

Paul will show that the same is true of people in the body of Christ. Christianity is not a club that can be joined and then quit later when it stops being enjoyable. Those who come to faith in Christ come for good. They are given a permanent place in an eternal organism. Believers who become discontent with their Spirit-given role in the body cannot simply give up serving that function or even quit belonging to Christ. It is who they are now.

The best they can do is to discover, or rediscover, how essential their function is to Christ and His body, as Paul shows in the following verse.