The army of Christ serving in this world is all the visible churches of Christ throughout the world, those that teach the Word of God. We are still in the spiritual warfare and suffering.
If you are not attached to a certain church, then you are not yet in the army of Christ. You have to serve in a physical unit. You join the army of Christ by being baptized into a particular church (or transferring your membership there from another church). Each particular church is a company or battalion in the Lord’s army. These are the people you worship with on the Lord’s day.
The smallest unit in the Army is the fire team made up usually of four or five soldiers. You need three or four men who are close friends with whom you can live in this world. You stay together. You praise one another, challenge one another, push one another, help one another, and serve alongside one another.
The Order of the Lion 