If we really understand love and live in love, most of the problems in church life would disappear.
God gave authority to the apostles so the church needed to listen to their word as the word of God.
The true gospel of justification by faith alone in contrast to the false gospel of justification of God's laws
The unity of all believers in Christ.
The joy of fellowship with God.
How to live knowing Christ is the only and all sufficient Saviour.
Future hope of the coming again of Christ.
Thins that must happen before the second coming of Christ.
Public worship and proper organization of the church.
Importance of sound doctrine in the church.
Salvation by sovereign grace alone - obedience of the law can't make us righteous before God.