Gerhard and Walther

Upon the justification and rebirth of a believing person there immediately follows the renewing of that person and the giving of the Holy Spirit. Indeed, this work of grace is inextricably connected to the former.—Johann Gerhard, Schola Pietatis, I:123ff.

Whoever wants to be a Christian must justify his faith before the world by the manner in which he conducts himself in his vocation.... In all our pursuits, let us demonstrate that faith makes us the best we can be. In this way, we justify our faith before the world.—C. F. W. Walther, God Grant It!, p. 141.