"Now all these works are done outside of faith, therefore they are nothing and altogether dead."
-- Martin Luther
I. We ought first to know that there are no good works except those which God has commanded, even as there is no sin except that which God has forbidden. Therefore whoever wishes to know and to do good works needs nothing else than to know God's commandments. Thus Christ says, Matthew xix, "If thou wilt enter into life, keep the commandments." And when the young man asks Him, Matthew xix, what he shall do that he may inherit eternal life, Christ sets before him naught else but the Ten Commandments. Accordingly, we must learn how to distinguish among good works from the Commandments of God, and not from the appearance, the magnitude, or the number of the works themselves, nor from the judgment of men or of human law or custom, as we see has been done and still is done, because we are blind and despise the divine Commandments.
II. The first and highest, the most precious of all good works is faith in Christ, as He says, John vi. When the Jews asked Him: "What shall we do that we may work the works of God?" He answered: "This is the work of God, that ye believe on Him Whom He hath sent." When we hear or preach this word, we hasten over it and deem it a very little thing and easy to do, whereas we ought here to pause a long time and to ponder it well. For in this work all good works must be done and receive from it the inflow of their goodness, like a loan. This we must put bluntly, that men may understand it.
We find many who pray, fast, establish endowments, do this or that, lead a good life before men, and yet if you should ask them whether they are sure that what they do pleases God, they say, "No"; they do not know, or they doubt. And there are some very learned men, who mislead them, and say that it is not necessary to be sure of this; and yet, on the other hand, these same men do nothing else but teach good works. Now all these works are done outside of faith, therefore they are nothing and altogether dead. For as their conscience stands toward God and as it believes, so also are the works which grow out of it. Now they have no faith, no good conscience toward God, therefore the works lack their head, and all their life and goodness is nothing. Hence it comes that when I exalt faith and reject such works done without faith, they accuse me of forbidding good works, when in truth I am trying hard to teach real good works of faith.
Luther, Martin (2009-10-04). A Treatise on Good Works (Kindle Locations 207-223). Public Domain Books. Kindle Edition.