Excerpt from - Christ the End of the Law, a sermon by C.H.Spurgeon

"And now, secondly, he is the law's fulfillment. It is impossible for any of us to be saved without righteousness. The God of heaven and earth by immutable necessity demands righteousness of all his creatures. Now, Christ has come to give to us the righteousness which the law demands, but which it never bestows. In the chapter before us we read of "the righteousness which is of faith," which is also called "God's righteousness"; and we read of those who "shall not be ashamed" because they are righteous by believing unto righteousness." What the law could not do Jesus has done. He provides the righteousness which the law asks for but cannot produce. What an amazing righteousness it must be which is as broad and deep and long and high as the law itself. The commandment is exceeding broad, but the righteousness of Christ is as broad as the commandment, and goes to the end of it. Christ did not come to make the law milder, or to render it possible for our cracked and battered obedience to be accepted as a sort of compromise. The law is not compelled to lower its terms, as though it had originally asked too much; it is holy and just and good, and ought not to be altered in one jot or tittle, nor can it be. Our Lord gives the law all it requires, not a part, for that would be an admission that it might justly have been content with less at first. The law claims complete obedience without one spot or speck, failure, or flaw, and Christ has brought in such a righteousness as that, and gives it to his people. The law demands that the righteousness should be without omission of duty and without commission of sin, and the righteousness which Christ has brought is just such an one that for its sake the great God accepts his people and counts them to be without spot or wrinkle or any such thing. The law will not be content without spiritual obedience, mere outward compliances will not satisfy. But our Lord's obedience was as deep as it was broad, for his zeal to do the will of him that sent him consumed him. He says himself, "I delight to do thy will, O my God, yea thy law is within my heart." Such righteousness he puts upon all believers. "By the obedience of one shall many be made righteous"; righteous to the full, perfect in Christ. We rejoice to wear the costly robe of fair white linen which Jesus has prepared, and we feel that we may stand arrayed in it before the majesty of heaven without a trembling thought. This is something to dwell upon, dear friends. Only as righteous ones can we be saved, but Jesus Christ makes us righteous, and therefore we are saved. He is righteous who believeth on him, even as Abraham believed God and it was counted unto him for righteousness. "There is therefore, now no condemnation to them that are in Christ Jesus," because they are made righteous in Christ. Yea, the Holy Spirit by the mouth of Paul challengeth all men, angels, and devils, to lay anything to the charge of God's elect, since Christ hath died. O law, when thou demandest of me a perfect righteousness, I, being a believer, present it to thee; for through Christ Jesus faith is accounted unto me for righteousness. The righteousness of Christ is mine, for I am one with him by faith, and this is the name wherewith he shall be called—"The Lord our righteousness."
Jesus has thus fulfilled the original demands of the law, but you know, brethren, that since we have broken the law there are other demands. For the remission of past sins something more is asked now than present and future obedience. Upon us, on account of our sins, the curse has been pronounced, and a penalty has been incurred. It is written that he "will by no means clear the guilty," but every transgression and iniquity shall have its just punishment and reward. Here, then, let us admire that the Lord Jesus Christ is the end of the law as to penalty. That curse and penalty are awful things to think upon, but Christ has ended all their evil, and thus discharged us from all the consequences of sin. As far as every believer is concerned the law demands no penalty and utters no curse. The believer can point to the Great Surety on the tree of Calvary, and say, "See there,oh law, there is the vindication of divine justice which I offer to thee. Jesus pouring out his heart's blood from his wounds and dying on my behalf is my answer to thy claims, and I know that I shall be delivered from wrath through him." The claims of the law both as broken and unbroken Christ has met: both the positive and the penal demands are satisfied in him. This was a labour worthy of a God, and lo, the incarnate God has achieved it. He has finished the transgression, made an end of sins, made reconciliation for iniquity, and brought in everlasting righteousness. All glory be to his name."

www.spurgeon.org/sermons/1325.htm