Jesus commanded His followers to "make disciples."
He told us that we need to teach them all I have commanded" (Matthew 28:18-20).
How can that happen if we do not know all the commands that He has given?
The Bible speaks of itself as being "breathed out by God and profitable for
teaching, for reproof, for correction and for training in righteousness,
that the man of God may be complete, equipped for every good work" (2 Timothy 3:16-17).
We grow in our faith by learning about who God is and how He wants us to live.