Rom 3 20Therefore no one will be declared righteous in his sight by observing the law; rather, through the law we become conscious of sin."

The Psalmist is putting this phrase used by the apostle in the context of the curse.  The quote through the law we become conscious of sin."is used by the Psalmist as an advantage.If we are teaching this phrase and sitting in the room next to a believer is an unbeliever they will not agree with this phrase. The believer will think that it is good because he is justified. But the unbeliever will not like it because he knows the law will condemn him. The knowledge of sin for a believer gives him the right to speak the curses.The Psalmist never views his sin in the context of gaining forgiveness from God. Even tho he confesses the sin yet it is used in a broader argument. Because we can use our weakness as an advantage then our personal knowledge of our sin prevents us from taking Gods vengeance into our own hands. If we cursed in the context of being sinless then we would be encouraged to use our own violence.  Our knowledge of sin reminds us that God does everything for us so that we are able to find solace by the consuming of our personal anger in Gods pronounced vengeance. So the unbeliever has a knowledge of sin that he is cursed by. 


Rom 10 17  Consequently, faith comes from hearing the message, and the message is heard through the word of Christ. But I ask: Did they not hear? Of course they did:"Their voice has gone out into all the earth, their words to the ends of the world."

The Psalmist is teaching that God created the world by speaking the law,covenants,curses,decrees,statutes and promises. The law, statutes and promises are pronouncements that are enforced by the covenants and curses. God governs the creation"Their voice has gone out into all the earth," and  nations through the axioms. Gods people where responsible to God by a covenant of circumcision. But they needed the covenant of grace in order to know the value of the pronouncements. Without grace they implemented the law through the physical markers and not the axioms. David fought the battle with the nations through pronouncing the axioms. He used the physical weapons as means to accomplish the axioms. Paul is teaching that citizens were condemned because their trust in the physical markers was unlawful. They needed the covenant of grace in order to exercise faith. 

Rom 11 7What then? What Israel sought so earnestly it did not obtain, but the elect did. The others were hardened, as it is written:"God gave them a spirit of stupor,eyes so that they could not see
       and ears so that they could not hear,
   to this very day."And David says:
   "May their table become a snare and a trap,
       a stumbling block and a retribution for them.
   May their eyes be darkened so they cannot see,
       and their backs be bent forever."
Through progressive revelation God established the covenant of creation through the Nation of Israel. God created man for His glory. He gave man ruler-ship over the creation in order to establish mans glory. The law of God was given to establish the rights of man to govern as Gods glory. God gave the law for the purpose of providing man with the ability to govern. God applies the law creating and governing and man applies the law in enjoying Gods provision. Perfect government produces ultimate freedom. The purpose of God giving man the law was to provide the freedom to enjoy the creation. But when man fell into sin , he began to redefine Gods law. Man introduced violence into the world. He began to apply Gods law unlawful.God created the parts to work according to His perfect law working in perfect unity. As man was able to apply the law he provided the highest pleasure in the success of others. But now he destroys others by redefining the law. He curses his neighbor. So sin brought destruction into society.
This is why the Psalmist complains that he is being opposed by the wicked by snares, stumbling blocks,sorrow that darkens the eyes and increases the pain of old age,and traps. The desire to curse ones neighbor comes from shame and guilt. The cursed communication is putting blame on others.If God had not added the curses to lawbreakers then the world would have been destroyed by war. So the only lawful defense of the wicked curse is the curse of the law. God gave the curses to show the violence of the smallest sin. Sin that becomes utterly sinful disables the sinner.God had to provide the pronouncements to apply allowing and preventing by the law. When we trust in our own vengeance we encourage more violence. This is why Gods pronouncements are violent speech. The wicked do not trust in Gods axioms. Gods elect seek Him lawfully through the pronouncements.