To ‘walk worthy’ is a key New Testament concept which calls the believer to live in a way that is consistent with his identification with the Lord who saved him. Being ‘fruitful in every good work’ refers to spiritual fruit, which is the byproduct of a righteous life. The Bible identifies spiritual fruit as leading people to Christ (1 Cor. 16:15), praising God (Heb. 13:15), giving money (Rom. 15:26-28), living a godly life (Heb. 12:11), and displaying holy attitudes (Gal. 5:22,23). Increasing in the knowledge of God – spiritual growth cannot occur apart from this knowledge (1 Pet. 2:2; 2 Pet. 3:18). The evidences of spiritual growth include a deeper love for God’s Word (Ps. 119:97), a more perfect obedience (1 John 2:3-5), a strong doctrinal foundation (1 John 2:12-14), an expanding faith (2 Thess. 1:3), and a greater love for others (Phil. 1:9).
Commentary from the MacArthur study Bible, notes for Colossians 1:10.