God’s covenant with us is prior to any covenant we make with each other. He chooses us, sets us apart, calls us to holiness, and enjoins us to love one another. But all this must happen in particulars. The commitment to live out the principles of the new covenant takes place with a specific people in a specific place. This results in a local church. Membership matters because particularization matters.
According to Jonathan Leeman (whose ideas I’ve borrowed in the paragraph above), submitting to a local church accomplishes a number of crucial things. Church membership:
1. Identifies us with Christ.
2. Distinguishes us from the world.
3. Guides us into the righteousness of Christ by presenting a standard of personal and corporate righteousness.
4. Acts as a witness to non-Christians.
5. Glorifies God and enables us to enjoy his glory.
6. Identifies us with God’s people.
7. Assists us in living the Christian life through the accountability of brothers and sisters in the faith.
8. Makes us responsible for specific believers.
9. Protects us from the world, the flesh, and the Devil.
In other words, “the covenant commitment of the local church makes the invisible new covenant visible. It’s an earthly symbol, sign, or analogy of this wonderful heavenly reality” (The Church and the Surprising Offense of God’s Love, 267).