What does it mean to be mature?
The Christian life begins with the new birth and progressively moves toward maturity in Christ, culminating in genuine love and good works.

God’s Gracious Work in the Church - Audio

The main work of ecclēsia is to build up the body of Christ by the consistent teaching of the Bible, book-by-book, chapter-by-chapter, verse-by-verse. The worship is simple, focusing on exalting the Lord.