What does Romans 12:4 mean?

Paul is describing how living sacrifices live. He has urged Christians—all who have received God's mercy because of their faith in Christ—to offer their everyday lives to God as an ongoing act of worship. Previous verses made clear that this will require transformation of our minds and perspective so that we can see and understand what God wants and be used by Him to get it done.

Now, though, Paul begins to get into what our specific jobs in this sacrificial lifestyle might be. It turns out that God's purpose for Christians is that we will spend our lives serving each other in specific ways. His analogy here applies broadly to each local congregation, but it also includes the worldwide church in general.

Paul uses the familiar analogy of a human body, something he develops in more detail in 1 Corinthians 12:12–31. Bodies are a unified whole, containing one person. But that unified body is made up of many different parts that serve wildly different functions from head to toe. Paul will show in the following verses that the church, meaning all Christians, is similar in that we are the body of Christ.