We should be thankful to the God the Father first, then God the Son, giving thanks in the name of Jesus Christ. All thanksgiving should be expressed through Christ.
"Let the peace of God rule . . . and be thankful" (verse 15).
"Let the word of Christ dwell in you" (verse 16).
"Do all in the name of the Lord Jesus" (verse 17).
Paul makes sure we understand that we must actively participate in order to grow. When God talks about growth, He means increasing in His attributes, the qualities that will conform us to His image.