Why does the church exist? Even if we can give the theologically correct question, what does it look like practically? The church exists, not for itself, but for mission—to carry out the mission that Jesus Christ gave to it. That mission is to embrace a biblical commitment to planting healthy, reproducing churches.
Therefore do not throw away your confidence, which has a great reward. For you have need of endurance, so that when you have done the will of God you may receive what is promised. — Hebrews 10:35-36 (ESV)