What a great thing it is when someone believes in Jesus Christ. This is cause for rejoicing, and that is exactly what Paul is doing. He is giving thanks for his fellow believers coming to faith. He also keeps them in his prayers. Paul knows that the Christian life is not complete after one believes. They must grow in their knowledge and love of Christ. They must continue to work out their salvation by putting off sin and putting on Christ, and Paul prays that God would do these things in their lives. As Christians, we have to continue to grow and progress in our faith. We have to daily call on the Lord to help us in this. Are you growing in your faith? Are you asking Jesus to help you overcome the sin in your life?