The question may arise about the Holy Spirit's role in the salvation of sinners. The answer is clear from Scripture. We are drawn by, convicted, born of, and kept by the Holy Spirit. Why then do we need to use the Law (10 Commandments) when witnessing? Jesus Himself tells us how the Holy Spirit works in the salvation of the lost. He said that when the Holy Spirit comes, "he will reprove the world of sin, (which is transgression of the Law; 1 John 3:4), and of righteousness, (which is of the Law ;Romans 8:4), and of judgement, (which is by the Law; Romans 2:12). So, when we use the Law to bring the knowledge of sin to the lost, we simply become instruments the Holy Spirit uses to lead sinners to the Savior. (1)
First of all, the Holy Spirit convicts us of sin. The definition for sin is found in 1 John 3:4, which says, "Whosoever commits sin transgresses also the law: for sin is the transgression of the law." I love the way John Wesley described the proper use of the Law, he said, " To slay the sinner is then the first use of the Law, to destroy the life and strength where in he trusts and convince him that he is dead while he lives: not only under the sentence of death, but actually dead to God, void of all spiritual life, dead in trespasses and sins." The Law exposes the sin in a person's heart. It brings to light the wickedness of sin. Charles Spurgeon said, "But the Law comes, takes the shutters down, lets light in, and then we discover what a vile heart we have, and how unholy our lives have been; and then, instead of boasting, we are made to fall on our faces and cry. 'Lord, save or I perish. Oh, save me for thy mercy's sake, or else I shall be cast away.'"
Next, the Holy Spirit shows us the righteousness of the Law. In Romans 7:12, it says" Wherefore the law is holy, and the commandment holy, and just, and good." When the Law was given on Mount Sinai, the people of Israel were afraid. They said unto Moses, " Speak thou with us, and we will hear: but let not God speak with us, lest we die." Exodus 20:19 Charles Spurgeon said," It was a dread Law even when it was given, and since then from that Mount Sinai an awful lava of vengeance has run down, to deluge, to destroy, to burn, and to consume the whole human race, if it had not been that Jesus Christ had stemmed its awful torrent, and bidden its waves of fire to be still." God had to provide another way to bring sinful men to a righteous God. He provided a way through His Son Jesus, who was the only person to keep the Law perfectly. The Bible says, "But now the righteousness of God, without the law, is manifested, being witnessed by the law and the prophets; Even the righteousness of God which is by faith of Jesus Christ unto all and upon all them that believe: for there is no difference." Romans 3:21-22 God provided His righteousness to those who trust in Jesus Christ, thus meeting the demands of the Law and fulfilling it to the letter."That the righteousness of the Law might be fulfilled in us, who walk not after the flesh, but after the Spirit." Romans 8:4 What a wonderful knowledge to have is that the righteous demands of the Law were met at Calvary, and we now have access to God by the blood of Christ!
Finally, the Holy Spirit shows us the judgement of God. "For as many as have sinned without the law shall also perish without the law, and as many as have sinned in the law shall be judged by the law". Romans 2:12 What is the standard by which we are judged? It is by the Law. Have you ever told a lie? Stolen anything? If yes, then you are a lying thief, and that is only two of the ten commandments. The Law are ten cannons that are pointed at you to blow away the fig leaves of your self righteousness. Charles Spurgeon said, " 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." Thus, the purpose of the Law is to lead people to Christ. A teacher that leads us to graduation. "Wherefore the Law was our schoolmaster to bring us unto Christ, that we might be justified by faith." Galatians 3:24
In conclusion, God is not willing that any should perish. God waits patiently for people to repent and trust in Jesus. By His mercy and restraint, He holds back His wrath, and does not yet judge people by the full measure of the Law. However, that restraint doesn't last forever. The Bible says, "But after your hardness and impenitent (not sorry) heart you treasure up to yourself wrath against the day of wrath and revelation of the righteous judgement of God; Who will render to every man according to his deeds." Romans 2:5-6 Imagine, a world being judged by the Law, which is why the Book of Revelation is so amazing. Let us use the Law lawfully while we still have time because the day of the Lord in near. Let us be like John the Baptist who said, "O generation of vipers, who hath warned you to flee from the wrath to come? Matthew 3:7