Whenever I reread the Old Testament Law, all I can say is, "Lord, how can I keep all of these without Your grace?" The reason is the Law can be followed to a certain extent by sinful man but to keep it completely is just impossible. James 2:10-11 and Romans 3:1-019 makes it clear that it takes only takes one violation of the Law to be considered a transgressor. To God, the person who stole candy is already worthy of Hell as the person who stole gold bars. Nobody can say, "But LORD, I stole candy, that wasn't a big offense?" Absolute holiness and perfection means there is nothing impure or unholy that will ever make it before the righteous standards of God's Law.
Galatians 3:24 says that the Law is the schoolmaster that brings us to faith in Christ. There is really and absolutely no salvation without the Law. The Law is not merely suggestions but they are commandments that you have to follow. When God tells you to do something you ought to do it. It cannot be dismissed as merely a suggestion. The Law not only sets things in order but it also shows people that they have violated the precepts of God. 1 Timothy 1:9 says that the Law was not made for righteous people but for sinners. As Martin Luther calls the Law, it is a mirror that exposes our ugliness and imperfections before a holy and righteous God. The more one sees the Law, the more one sees the ugliness and imperfection of the lost sinner.
Using the Ten Commandments in preaching and soulwinning is not works salvation but shows sinners their need for salvation. I remembered Ray Comfort's evangelism that asks people about the ten commandments to show them their sinfulness. The standard of the Law is impossible to keep. Do you remember the rich young ruler who said, "All these have I kept since childhood?" While the story is misused by the works crowd to justify their heresy, the "Easy Christianity" crowd do not see the full meaning of it as well. When Jesus said to the rich young ruler that he lacked one thing, it showed our helplessness to keep the whole Law. The rich young ruler sought to justify himself when he said, "All these I have kept since youth." I cannot say yes to that and that's why I need to be saved from my sins because I myself cannot do it.
God's grace also means nothing to a person who loves their sin. As I mentioned earlier, many people that they are right with God but their lifestyles show that they are lost. It is like a person who attends Sunday services, prays the Rosary a lot, tries to be as religious as possible while engaging in several vices such as womanizing, gambling, alcoholism that such shall not inherit God's Kingdom (1 Corinthians 6:9-10). If people love their sin then true salvation means nothing to them because they want salvation to sin and not from sin. False converts do not want a real Gospel preaching because they want to sin all they please. They want to believe Jesus died so they can sin all they please not the grace to live a life pleasing to God. Many of them think they are saved because of some degree of good works but their lifestyle shows that they are lost as ever.