Paul says that the power of sin is the law. The more clearly we understand the law, the more sin oppresses and stings us.
“The words “it was counted to him” were not written for his sake alone, but for ours also. It will be counted to us who believe in him who raised from the dead Jesus our Lord, who was delivered up for our trespasses and raised for our justification.” (Romans 4:23-25)
This is the meaning of the words by St. Paul: "Christ was raised for our justification." Here Paul turns my eyes away from my sins and directs them to Christ, for if I look at my sins, they will destroy me. Therefore, I must look unto Christ who has taken my sins upon himself, crushed the head of the serpent and become the blessing. Now they no longer burden my conscience, but rest upon Christ, whom they desire to destroy. Let us see how they treat him. They hurl him to the ground and kill him. O God; where is now my Christ and my Savior? But then God appears, delivers Christ and makes him alive; and not only does he make him alive, but he translates him into heaven and lets him rule over all.
What has now become of sin? There it lies under his feet. If I then cling to this, I have a cheerful conscience like Christ, because I am without sin. Now I can defy death, the devil, sin, and hell to do me any harm. As I am a child of Adam, they can indeed accomplish it that I must die. But since Christ has taken my sins upon himself, has died for them, has suffered himself to be slain on account of my sins, they can no longer harm me; for Christ is too strong for them, they cannot keep him, he breaks forth and overpowers them, ascends into heaven, and rules there over all throughout eternity. Now I have a clear conscience, am joyful and happy and am no longer afraid of this tyrant, for Christ has taken my sins away from me and made them his own. But they cannot remain upon him; what then becomes of them? They must disappear and be destroyed. This then is the effect of faith. He who believes that Christ has taken away our sin, is without sin, like Christ himself, and death, the devil and hell are vanquished as far as he is concerned and they can no longer harm him.
Here we also refer to the passage in Hosea 13:14, which Paul quotes in reference to the victory that Christ has won by his resurrection and by which he has conquered sin, death, hell and all our enemies. Paul says that death is swallowed up in this victory, and he defies death with these words: "O death, where is thy victory? O death, where is thy sting?" just as if Paul would say: O death, where are thy teeth? Come, bite off one of my fingers. You formerly had a spear, what has become of it now? Christ has taken it from you. Death, where is now your spear, etc.? Sin, where is now the edge of your sword and your power?
Paul says that the power of sin is the law. The more clearly we understand the law, the more sin oppresses and stings us. For this reason, Paul says that Christ has completely destroyed and annihilated the spear and whetstone of death. Now, this Gospel he has not taken with him into heaven, but he caused it to be preached throughout the world, so that for him who believes in Christ, spear and whetstone, sin and death, should be destroyed. This is the true Gospel, which bestows life, strength, power, and marrow, and of which all the passages of Scripture speak.