Faith must be the mother and source of works that are truly good and well pleasing to God. St. Paul calls them true fruit of faith, also fruit of the Spirit. For, as Dr. Luther writes in the Preface to St. Paul's Epistle to the Romans:
Faith, however, is a divine work in us that changes us and makes us to be born anew of God, John 1. It kills the old Adam and makes us altogether different men, in heart and spirit and mind and powers; it brings with it the Holy Spirit. O, it is a living, busy, active, mighty thing, this faith. It is impossible for it not to be doing good works incessantly. It does not ask whether good works are to be done, but before the question is asked, it has already done them, and is constantly doing them. Whoever does not do such works, however, is an unbeliever.
Faith is a living, daring confidence in God's grace, so sure and certain that the believer would stake his life on it. This knowledge of and confidence in God's grace makes men glad and bold and happy in dealing with God and all creatures. And this is the work that the Holy Spirit performs in faith. Because of it, without compulsion, a person is ready and glad to do good to everyone, to serve everyone, to suffer everything, out of love and praise to God, who has shown him this grace. Thus it is impossible to separate works from faith. (paragraphs 9-12)
Condensed from CONCORDIA: THE LUTHERAN CONFESSIONS, copyright 2005,2006 by Concordia Publishing House. Used by permission. All rights reserved. To purchase a copy of CONCORDIA, call 800-325-3040.