True, this is an interpretation not directly suggested by the narrative and the text. Paul himself calls it an allegory; that is, a mystic narrative, or a story with a hidden meaning. But he does not say that the literal text is necessarily the letter that killeth, and the allegory, or hidden meaning, the spirit. But the false teachers assert of all Scripture that the text, or record itself, is but a dead "letter," its interpretation being "the spirit." Yet they have not pushed interpretation farther than the teaching of the Law; and it is precisely the Law which Paul means when he speaks of "the letter."*
* What Luther means is that the popish theologians with their vaunted "spiritual" interpretation had never penetrated to the Gospel, which confers the life in the Spirit, but had satisfied themselves with so literal and superficial an interpretation of the Law as to seek salvation through work-righteousness.
21. Paul employs the word "letter" in such contemptuous sense in reference to the Law—though the Law is, nevertheless, the Word of God—when he compares it with the ministry of the Gospel. The letter is to him the doctrine of the Ten Commandments, which teach how we should obey God, honor parents, love our neighbor, and so on—the very best doctrine to be found in all books, sermons and schools.
The word "letter" is to the apostle Paul everything which may take the form of doctrine, of literary arrangement, of record, so long as it remains something spoken or written. Also thoughts which may be pictured or expressed by word or writing, but it is not that which is written in the heart, to become its life. "Letter" is the whole Law of Moses, or the Ten Commandments, though the supreme authority of such teaching is not denied. It matters not whether you hear them, read them, or reproduce them mentally. For instance, when I sit down to meditate upon the first commandment: "Thou shalt have no other gods before me," or the second, or the third, and so forth, I have something which I can read, write, discuss, and aim to fulfil with all my might. The process is quite similar when the emperor or prince gives a command and says: "This you shall do, that you shall eschew." This is what the apostle calls "the letter," or, as we have called it on another occasion, the written sense.
22. Now, as opposed to "the letter," there is another doctrine or message, which he terms the "ministration of a New Covenant" and "of the Spirit." This doctrine does not teach what works are required of man, for that man has already heard; but it makes known to him what God would do for him and bestow upon him, indeed what he has already done: he has given his Son Christ for us; because, for our disobedience to the Law, which no man fulfils, we were under God's wrath and condemnation. Christ made satisfaction for our sins, effected a reconciliation with God and gave to us his own righteousness. Nothing is said in this ministration of man's deeds; it tells rather of the works of Christ, who is unique in that he was born of a virgin, died for sin and rose from the dead, something no other man has been able to do. This doctrine is revealed through none but the Holy Spirit, and none other confers the Holy Spirit. The Holy Spirit works in the hearts of them who hear and accept the doctrine. Therefore, this ministration is termed a ministration "of the Spirit."
23. The apostle employs the words "letter" and "spirit," to contrast the two doctrines; to emphasize his office and show its advantage over all others, however eminent the teachers whom they boast, and however great the spiritual unction which they vaunt. It is of design that he does not term the two dispensations "Law" and "Gospel," but names them according to the respective effects produced. He honors the Gospel with a superior term—"ministration of the spirit." Of the Law, on the contrary, he speaks almost contemptuously, as if he would not honor it with the title of God's commandment, which in reality it is, according to his own admission later on that its deliverance to Moses and its injunction upon the children of Israel was an occasion of surpassing glory.
24. Why does Paul choose this method? Is it right for one to despise or dishonor God's Law? Is not a chaste and honorable life a matter of beauty and godliness? Such facts, it may be contended, are implanted by God in reason itself, and all books teach them; they are the governing force in the world. I reply: Paul's chief concern is to defeat the vainglory and pretensions of false preachers, and to teach them the right conception and appreciation of the Gospel which he proclaimed. What Paul means is this: When the Jews vaunt their Law of Moses, which was received as Law from God and recorded upon two tables of stone; when they vaunt their learned and saintly preachers of the Law and its exponents, and hold their deeds and manner of life up to admiration, what is all that compared to the Gospel message? The claim may be well made: a fine sermon, a splendid exposition; but, after all, nothing more comes of it than precepts, expositions, written comments. The precept, "Thou shalt love the Lord thy God with all thy heart, and thy neighbor as thyself," remains a mere array of words. When much time and effort have been spent in conforming one's life to it, nothing has been accomplished. You have pods without peas, husks without kernels.
25. For it is impossible to keep the Law without Christ, though man may, for the sake of honor or property, or from fear of punishment, feign outward holiness. The heart which does not discern God's grace in Christ cannot turn to God nor trust in him; it cannot love his commandments and delight in them, but rather resists them. For nature rebels at compulsion. No man likes to be a captive in chains. One does not voluntarily bow to the rod of punishment or submit to the executioner's sword; rather, because of these things, his anger against the Law is but increased, and he ever thinks: "Would that I might unhindered steal, rob, hoard, gratify my lust, and so on!" And when restrained by force, he would there were no Law and no God. And this is the case where conduct shows some effects of discipline, in that the outer man has been subjected to the teaching of the Law.
26. But in a far more appalling degree does inward rebellion ensue when the heart feels the full force of the Law; when, standing before God's judgment, it feels the sentence of condemnation; as we shall presently hear, for the apostle says "the letter killeth." Then the truly hard knots appear. Human nature fumes and rages against the Law; offenses appear in the heart, the fruit of hate and enmity against the Law; and presently human nature flees before God and is incensed at God's judgment. It begins to question the equity of his dealings, to ask if he is a just God. Influenced by such thoughts, it falls ever deeper into doubt, it murmurs and chafes, until finally, unless the Gospel comes to the rescue, it utterly despairs, as did Judas, and Saul, and perhaps pass out of this life with God and creation. This is what Paul means when he says (Rom 7, 8-9) that the Law works sin in the heart of man, and sin works death, or kills.
27. You see, then, why the Law is called "the letter": though noble doctrine, it remains on the surface; it does not enter the heart as a vital force which begets obedience. Such is the baseness of human nature, it will not and cannot conform to the Law; and so corrupt is mankind, there is no individual who does not violate all God's commandments in spite of daily hearing the preached Word and having held up to view God's wrath and eternal condemnation. Indeed, the harder pressed man is, the more furiously he storms against the Law.