"Such is the confidence that we have through Christ toward God. Not that we are sufficient in ourselves to claim anything as coming from us, but our sufficiency is from God, who has made us sufficient to be ministers of a new covenant, not of the letter but of the Spirit. For the letter kills, but the Spirit gives life. Now if the ministry of death, carved in letters on stone, came with such glory that the Israelites could not gaze at Moses' face because of its glory, which was being brought to an end, will not the ministry of the Spirit have even more glory? For if there was glory in the ministry of condemnation, the ministry of righteousness must far exceed it in glory. Indeed, in this case, what once had glory has come to have no glory at all, because of the glory that surpasses it. For if what was being brought to an end came with glory, much more will what is permanent have glory." -2 Cor. 3:4-11 (ESV)
When man, conscious of his failure to keep God's command, is constantly urged by the Law to make payment of his debt and confronted with nothing but the terrible wrath of God and eternal condemnation, he cannot but sink into despair over his sins. Such is the inevitable consequence where the Law alone is taught with a view to attaining heaven through it. The vanity of such trust in works is illustrated in the case of the noted hermit mentioned in Vitae Patrum. For over seventy years this hermit had led a life of utmost austerity, and had many followers. When the hour of death came he began to tremble, and for three days was in a state of agony. His disciples came to comfort him, exhorting him to die in peace since he had led so holy a life. But he replied: "Alas, I truly have all my life served Christ and lived austerely; but God's judgment greatly differs from that of men."
Note, this worthy man, despite the holiness of his life, has no acquaintance with any article but that of the divine judgment according to the Law. He knows not the comfort of Christ's Gospel. After a long life spent in the attempt to keep God's commandments and secure salvation, the Law now slays him through his own works. He is compelled to exclaim: "Alas, who knows how God will look upon my efforts? Who may stand before him?" That means, to forfeit heaven through the verdict of his own conscience. The work he has wrought and his holiness of life avail nothing. They merely push him deeper into death, since he is without the solace of the Gospel, while others, such as the thief on the cross and the publican, grasp the comfort of the Gospel, the forgiveness of sins in Christ. Thus sin is conquered; they escape the sentence of the Law, and pass through death into life eternal.
Paul is in an ecstasy of delight, and his heart overflows in words of praise for the Gospel. Again he handles the Law severely, calling it a ministration, or doctrine, of death and condemnation. What term significant of greater abomination could he apply to God's Law than to call it a doctrine of death? (2 Cor 3:7) And again, he calls it a "minister or preacher of sin” (Gal 2:17) and the message which proclaims a curse, saying, "As many as are of the works of the law are under a curse." (Gal 3:10) Absolute, then, is the conclusion that Law and works are powerless to justify before God; for how can a doctrine proclaiming only sin, death and condemnation justify and save?
Paul speaks this way because of the infamous presumption of both teachers and pupils, in that they permit flesh and blood to flirt with the Law. And in doing so, make their own works which they bring before God as their boast. Yet, nothing is effected but self-deception and destruction. For, when the Law is viewed in its true light, when its "glory" is revealed (2 Cor 3:7), it is found to do nothing more than to kill man and sink him into condemnation.
Therefore, the Christian will do well to learn these texts of Paul and have an armor against the boasting of false teachers, and the torments and trials of the devil when he urges the Law and induces men to seek righteousness in their own works, tormenting their heart with the thought that salvation is dependent upon the achievements of the individual. The Christian will do well to learn this text, so that in such conflicts he may take the devil's own sword, saying: "Why do you annoy me with talk of the Law and my works? What is the Law after all, however much you may preach it to me, but that which makes me feel the weight of sin, death and condemnation? Why should I seek righteousness before God there?"
When the glory and holiness of Christ, revealed through the preaching of the Gospel, is rightly perceived then the glory of the Law--which is but a feeble and transitory glory--is seen to be not really glorious. It is mere dark clouds in contrast to the light of Christ shining to lead us out of sin, death and hell unto God and eternal life.
(This is from a sermon preached by Martin Luther)