From these things we see, then, in the first place, how perilous those doctrines be which by commandment and law drive the man to the opinion that he is made godly thereby. For in this way they only tear him further and further from God, from Christ, yea, even from the Law and all righteousness— they do no more than to make the conscience increasingly fearful, faint, hopeless, and broken, ever teaching it to fear death and hell until that it drive utter doubt into the heart, so that both here and hereafter the man must play martyr to the devil.
In the second place, we see that there are three uses of the Law, or that men react [or stand in relation] to the Law in three different ways: The first [group], who take the risk and brazenly contradict it with an unrestrained life— to these it is as if there were no law; the second, who by it abstain from such a dissolute life and are preserved in an honorable life, and thus walk in discipline [Zucht] outwardly but inwardly are hostile to the schoolmaster [Zuchtmeister, disciplinarian, 1 Cor. 4:15, Gal. 3:24]; all their activity proceeds from the fear of death and hell, and thus they regard the Law merely outwardly— yea, the Law is their keeper outwardly; inwardly they neither keep it nor are kept by it. The third group keep it outwardly and inwardly.
They are the tables of Moses, engraved without and within by the Finger of God Himself. Now therefore, as the first are godly neither outwardly nor inwardly so the second are good only outwardly and not in their heart. But these last are thoroughly good. Of them St. Paul says (1 Tim. 1[:8]): “We know that the Law is good, whoever uses it rightly.” How then is it used rightly? He answers: “Whoever knows that to the righteous no law is given, but to the unrighteous.” What does that mean? Nothing else than that he that would preach the Law rightly must distinguish these three: that he by no means preach the Law to the third in a manner as if they should become godly thereby, for that would be deception [Verführerei = Verführung]. Howbeit to the first it is to be preached in this manner, that it has been set down [established, instituted by law] that they should leave their brazen life and be preserved under the schoolmaster. But it is not sufficient that they be thus preserved and kept by the Law; they must in turn also learn to keep the Law; it is then necessary to preach more and in addition to the Law the Gospel also, wherein Christ will give grace to keep the Law. Thus it is an entirely different thing to preserve or keep the Law and to be preserved or kept by the Law. The first neither keep it nor are kept by it, the second are kept [by it], the third keep [it].
(Blessed Martin Luther, Luthers Werke: Kritische Gesamtausgabe [Scriften] WA 10.1:456-457; trans. Matthew Carver)