Paul said that through Christ he had recieved grace and apostleship for the obedience of faith among all nations. (Rom. 1:5). True faith is obedience. "This is the work of God, that ye believe on Him whom He has sent" (John 6:29). Christ said, "Why call ye me, Lord, Lord, and do not the things which I say?" (Luke 6:46). That is, a profession of faith in Christ which is not accompanied by obedience, is worthless. "Faith if it hath not works, is dead" (Ja. 2:17). "For as the body without the spirit is dead, so faith without works is dead also" (Ja. 2:26).
A man does not breathe in order to show that he lives, but because he is alive. He lives by breathing. His breath is his life. So a man cannot do good works in order to demonstrate that he has faith, but he does good works because the works are the necessary result of faith. Even Abraham was justified by works, because "faith wrought with his works, and by works was faith made perfect. And the scripture was fulfilled which saith, Abraham believed God, and it was imputed unto him for righteousness" (Ja. 2:22, 23).
"Waggoner on Romans" : Ellet J. Waggoner : p. 1.13