Here is more gold from Luther’s commentary on Galatians (specifically 3.19). I found this while studying Q/A 3 of the Heidelberg Catechism in sermon preparation. It has to do with the purpose of the law.
“The fatuous [silly] idea that a person can be holy by himself denies God the pleasure of saving sinners. God must therefore first take the sledge-hammer of the Law in His fists and smash the beast of self-righteousness and its brood of self-confidence, self-wisdom, self-righteousness, and self-help. When the conscience has been thoroughly frightened by the Law it welcomes the Gospel of grace with its message of a Savior who came into the world, not to break the bruised reed, nor to quench the smoking flax, but to preach glad tidings to the poor, to heal the broken-hearted, and to grant forgiveness of sins to all the captives.”
“Man’s folly, however, is so prodigious [great in degree] that instead of embracing the message of grace with its guarantee of the forgiveness of sin for Christ’s sake, man finds himself more laws to satisfy his conscience. “If I live,” says he, “I will mend my life. I will do this, I will do that.” Man, if you don’t do the very opposite, if you don’t send Moses with the Law back to Mount Sinai and take the hand of Christ, pierced for your sins, you will never be saved. When the Law drives you to the point of despair, let it drive you a little farther, let it drive you straight into the arms of Jesus.”
That’s worth printing out and putting in a place where you can read it each day! Also, this is why John Newton once said that “ignorance of the nature and design of the law is at the bottom of most religious mistakes.” We have to understand the purpose of the law if we want to rightly understand the gospel of grace. The law shows us our sin, the gospel saves us from it.