Acts 13:38-43. On the 1st Missionary trip, Paul & Barnabas persuaded the people to continue in the grace of God. They started by grace through faith, without works or merit and must continue in that same grace.

Act 13:38-39. In his 1st recorded Sermon Paul clearly spells out Justification by faith for whoever believes. Showing that through the forgiveness of Christ you can be justified as you could never be under the law of Moses.