Why should [Jesus] die if there were no sin or law for which he must die? It is apparent from this that the devil’s purpose in this fanaticism is not to remove the law but to remove Christ, the fulfiller of the law.
For he is well aware that Christ can quickly and readily be removed, but that the law is written in the depth of the heart and cannot be erased. This is clearly seen in the psalms of lamentation. For here the dear saints are unable to bear the wrath of God. This is nothing but the law’s perceptible preaching in man’s conscience. The devil knows very well too that it is impossible to remove the law from the heart. In Romans 2 St. Paul testifies that the Gentiles who did not receive the law from Moses and thus have no law are nevertheless a law to themselves, being obliged to witness what the law requires is written in their hearts, etc. But the devil devotes himself to making men secure, teaching them to heed neither law nor sin, so that if sometime they are suddenly overtaken by death or a bad conscience, they have grown so accustomed to nothing but sweet security that they sink helplessly into hell. For they have learned to perceive nothing in Christ but sweet security. Therefore such terror must be a sure sign that Christ (whom they understand as sheer sweetness) has rejected and forsaken them. That is what the devil strives for, and what he would like to see.
It seems to me that these spirits think that all who are listening to the message are pure Christians, without sin—thou in reality they are dejected and downcast hearts who feel their sin and fear God and who therefore must be comforted. To such, the dear Jesus can never be portrayed sweetly enough. They need much more of this, as I discovered in many of them0—to say nothing of myself. But these spirits themselves are not such Christians, for they are so secure and confident. Neither are their listeners, who also are secure and happy. In one passage a find, beautiful young woman, a splendid singer, sings thus: “He feeds the hungry so that they rejoice, and sends the rich empty away. He humbles the mighty and exalts the lowly, and his grace is with those who fear him” [Luke 1:50-53]. If the Magnificat speaks the truth, then God must be the foe of the secure spirits who are unafraid, as such spirits who do away with law and sin are sure to be.
Therefore I ask you, dear Doctor, to keep to the pure doctrine as you have always done. Preach that sinners must be roused to repentance not only by the sweet grace and suffering of Christ, by the message that he died for us, but also by the terrors of the law.
Luther, “Against the Antinomians”