"The law of the Lord is perfect, converting the soul..."
2) To Stop Every Mouth & Leave the Whole World Guilty Before God - Romans 3:19
"that every mouth may be stopped and all the world may become guilty before God."
3) Brings the Knowledge of Sin - Romans 3:20
"for by the law is the knowledge of sin."
"I had not known sin but by the law." Romans 7:7
4) Defines Sin - 1 John 3:4
"sin is transgression of the law."
5) Schoolmaster to Lead us to Christ - Galatians 3:24
"For the law was our schoolmaster to bring us unto Christ, that we might be justified by faith."
6) To Condemn Us - John 3:18
"he who believes not is condemned already."
7) Makes Sin Exceedingly Sinful - Romans 7:13
"that sin by the commandment might become exceedingly sinful."
Saints, without God's Holy Law sinners won't see their sin, or how it is exceedingly sinful, and their heart will be unprepared for the Gospel. The Law simply exposes our nature, shows us our sin, leaves us guilty before a Just and Holy God, it stops our mouth from justifying ourselves, it completely condemns us, it makes our sin exceedingly sinful, and it leads us to Christ. The Law of God leaves us hopeless and helpless showing us our desperate need for saving. When we see ourselves as God sees us, we can then be humbled to see just how much we need His righteousness. Jesus Christ bore God's wrath on our behalf for us. He perfectly satisfied the demands of the Law of God. God's righteousness was met in Christ and His punishment was poured out on His son as Jesus fulfilled the Law in our stead. It leaves us absolutely and desperately worthless before God's throne. Yet we must preach it in order to lead men to Christ. How can a man see his need for the savior and appreciate and appropriate God's Grace without a full understanding of himself in the mirror and light of God's Law?
"I do not believe that any man can preach the Gospel who does not preach the Law...Lower the Law and you dim the light by which man perceives his guilt; this is a very serious loss to the sinner rather than a gain; for it lessens the likelihood of his conviction and conversion. I say you have deprived the gospel of its ablest auxiliary [its most powerful weapon] when you have set aside the Law. You have taken away from it the schoolmaster that is to bring men to Christ...They will never accept grace till they tremble before a just and holy Law. Therefore the Law serves a most necessary purpose, and it must not be removed from its place."