To establish the churches in the Faith!
Acts 16:4 (KJV) And as they went through the cities, they delivered them the decrees for to keep, that were ordained of the apostles and elders which were at Jerusalem.
Acts 16:5 (KJV) And so were the churches established in the faith, and increased in number daily.
2 Peter 1:12 (KJV) Wherefore I will not be negligent to put you always in remembrance of these things, though ye know them, and be established in the present truth.