Polity is not essential to salvation.
However, that does not mean that polity is not important – even important to the gospel itself. Faith begets order. The gospel seeds sprout into the tree of the church. So the gospel must be first. Dr. Tom Nettles talks about having a “theologically integrated ecclesiology.” By this approach, the best things about a church are the things that they have in common with all true gospel churches in all areas and eras.
However, there is a particular polity that comes naturally from the gospel. Polity is formed by the gospel and has a gospel shape. One cannot attempt to hold to the gospel but then leave polity in the realm of indifference. That approach always leads to pragmatism over the long run and will tend to lose the gospel over time. So to be serious about polity is to be serious about the gospel. Polity is what makes a local church a local church. It is what marks the institution God has given to make the gospel visible and reflect His character.
Simply put, God has not left questions of polity up for our invention. Polity is important even if just for the sole fact that God has told us in His Word what we are supposed to do and think about the church. We will function best, even pragmatically in the best sense, when we are obedience to the way that God has ordered things. It is interesting that we often check everything we usually do when trying to see what God’s Word has to say about a specific area of theology at the door when thinking about the church. We have been given a specific prescription for normative church government because the wise God of the universe has determined that His church is most glorifying to Him in their enjoyment of Him when they organize themselves according to His Word. God is wiser than man. But Polity is also important for the individual Christian. Polity gives the Christian life its institutional shape. The Christian is not to use the church only as a personal aid for discipleship and spiritual growth. Instead, the Christian’s identity is tied up in the local church. He is accountable to the members by virtue of covenant, not just because they have “let them into their life.”
Polity is created by the gospel. The gospel that demands true conversion and a life of faith and repentance necessitates the right use of the ordinances, membership and discipline. Church discipline shows how we view the gospel who and what. Polity also preserves and protects the gospel. Congregationalism protects the gospel by making members know the gospel and can spot true from false. Then, if the elders were to preach a false gospel, God has given His church the tools to remove that elder and protect the name of Christ and the well being of His sheep.
Have you ever been to a museum and seen one of those spectacular diamonds on display? These diamonds are not like other diamonds. They are so big and so clear! They are beautiful. People come from all around to see the diamond. Now usually these diamonds aren’t just placed on a table. They are held up by prongs or a kind of diamond holder. No one would come to see the diamond holder – it is not nearly as important as the diamond. But does that make it negligible? No way! Without it, the diamond would fall to the ground and shatter over time.
Polity is not the diamond, but it is the diamond holder. The gospel is the diamond. Without polity the diamond of the gospel, overtime is liable to fall. To be serious about the diamond holder, then, is to be serious about the diamond. The church will fulfill its mission to glorify God by enjoying Him forever by being rigorously careful about how it is governed.