I Corinthians 12 - Overview of Spiritual Gifts
If it's true that the church is the Body of Christ then what we do for the building up of the church is not volunteer service. What we do is the part that God created, called, and is shaping us to be.
As we do a flyby over I Corinthians 12 see all of the times that Paul, the pastor if this church in Corinth, underlines that God is the one who has arranged the parts. And, all of these parts are united, then, because He is the one who has placed and put them together.