Classic Luther (from his commentary on Galatians 2:16):
Of course, we must also teach good works and love, but it must be done in the right time and place—that is, when we are dealing with works, not justification. Here the question is how we are justified and attain eternal life, and so we reject and condemn all good works, for this passage will not allow any argument based on good works.
Indeed, “the law is holy, and the commandment is holy, righteous and good” (Romans 7:12). But when we are dealing with justification, it is not the time or place to speak about the law. The question is, who is Christ, and what benefit has he brought us? Christ is not the law; he is not what I have done or what the law has done; he is not my love, my obedience, my poverty. He is the Lord of life and death, a mediator, the Savior, the redeemer of those who are under the law and sin. By faith we are in him and he in us. The bridegroom must be alone with the bride in his private room, and all the servants and family must leave them. But afterwards, when the door is open and he comes out, then the servants may return to serve them. Then love and good works may do what they ought to do.