Thus faith is a divine work in us, that changes us and regenerates us of God, and puts to death the old Adam, makes us entirely different men in heart, spirit, mind, and all powers, and brings with it [confers] the Holy Ghost. Oh, it is a living, busy, active, powerful thing that we have in faith, so that it is impossible for it not to do good without ceasing. [11]](
http://bookofconcord.org/sd-goodworks.php#para11) Nor does it ask whether good works are to be done; but before the question is asked, it has wrought them, and is always engaged in doing them. But he who does not do such works is void of faith, and gropes and looks about after faith and good works, and knows neither what faith nor what good works are, yet babbles and prates with many words concerning faith and good works. [12]](
http://bookofconcord.org/sd-goodworks.php#para12) [Justifying] faith is a living, bold [firm] trust in God’s grace, so certain that a man would die a thousand times for it [rather than suffer this trust to be wrested from him]. And this trust and knowledge of divine grace renders joyful, fearless, and cheerful towards God and all creatures, which [joy and cheerfulness] the Holy Ghost works through faith; and on account of this, man becomes ready and cheerful, without coercion, to do good to every one, to serve every one, and to suffer everything for love and praise to God, who has conferred this grace on him, so that it is impossible to separate works from faith, yea, just as impossible as it is for heat and light to be separated from fire.
-Luther.