Paul exhorts the Philippians to follow his example, and he says that if you practice these things, the God of peace will be with you (Phil. 4:9).
First, remember that one of the examples that Paul left in all the churches was this meal: the Lord’s Supper. This meal is also called Communion, and communion is enacting peace. In your sin, you are at war with God. And once you were enemies of God. You hated God. But God reconciled you to Himself: He took your anger, your rebellion, and He laid it on Jesus on the cross and took it all away. In this way God made peace with you. But God offers this to everyone, and everyone who believes in Him is made right with Him. By faith, the blood of Christ washes you clean, and this includes all the ways we have sinned against one another. The blood of Christ washes away every harsh word, every lie, every betrayal, and this is why we have just greeted one another in the Peace of the Lord.
This meal is our Peace with God and our Peace with one another. But all of this requires faith. You are not at Peace with God because everyone thinks you’re at peace with God. You’re not at peace with everyone around you because everyone just assumes you are. You are at peace with God only by believing in Christ, resting in Him, crying out to Him. You are not at peace by eating bread and wine; you are at peace by faith in the broken body and shed blood of Jesus, the Lamb of God.
Sometimes Christians try really hard to be good, and yet they have no peace and they continually fail. And the reason is because they’re not trusting in Christ. They’re looking around at everyone around them and trying to mimic godliness. They’re trying to gin up their own peace through the approval of others. But if your salvation is a car, it is meant to drive. But some people grow up in the church and think that because the windows are down and they feel a bit of a breeze they must be driving. Or maybe they put it in neutral and push the car a few feet and think they’ve really made it somewhere. But your salvation was made to run, your salvation was made to drive, and the key to starting the engine is faith. Without faith you can do nothing, but by faith all things are yours because all things belong to Christ, and by faith you have peace with Him and He promises to meet you here.