To Luther the interrelatedness of faith and love was of first importance. His separation from Catholicism signified a parting of the way also in this respect. He had adequate experience of the fact that outward works were no guarantee of inner attitude. The new insight taught him that even as our righteousness is Christ’s righteousness, so also our works of love are Christ’s works in us. They ripen of themselves as fruit on a tree. From this spontaneity it follows that works must come after faith, and that if there are no works then faith cannot be true but is “acquired” (acquisita), in other words, self-made in some fashion. But the matter of works must not be put into the form of a demand. The demand as such would imply that faith is not real and needs something to complete it. True faith knows no demands, for the works of faith come of themselves. Faith rejoices in being able to clothe itself in works. Demands cannot improve the character of faith in any way. Faith it true if the relationship to God is true. Demands, however, are unable to improve the God-relationship. True faith and premeditated works for merit are contradictory, for true faith rests on what God does while works of merit reflect man’s own activity. Works that do not originate in faith are apt to lead a person into false notions about the true works of faith; they lead one to imagine works of faith where none exist. The distinction between true and false works, however, is a difficult as the distinction between true and false faith. No theory is adequate. One must believe, pray, and strive.
The works of faith issue forth from the spring of God’s abundant goodness. No human activity is comparable, for God and man are not comparable and all that a man does is really done by God. For this reason even the thought of merit before God is absurd. The grace of baptism already is so great that no human works can compare. Thereby “daring fools gain heaven and are blessed,” that is, those who properly trust in this gift of God without offering their own works as merit to God. The works of faith come spontaneously.
While Catholicism looked upon sanctification as a continuous activity on man’s part, as cultivation of self, as “school,” Luther saw it theocentrically: God does everything. Man’s struggle is a struggle for faith, not for works. Faith involves the total man, totally. Faith cannot result in inactivity, for it lives by God’s judgment and grace, which in turn give rise to the activity of faith. If something is lacking, it at once becomes a matter of faith. The activity of faith is the service of fellow man; the fellow man is therefore an inseparable part of faith. The aim of faith can never be merely one’s own salvation.
Faith Victorious: An Introduction to Luther’s Theology by Lennart Pinomaa, translated by Walter J. Kukkonen, pages 76-77