Law only arouses sinful lusts (Romans 7:8), so when you’re under Law (i.e. not born again or living in bondage as a born again person because of incomplete revelation of all that Jesus has given us), sin rules over you, and it produces death in your life – ultimately spiritual death in the unbeliever but temporal death in the life of the believer in the form of bondage to sin (Romans 6:16) and reaping the fruit of fleshly living (Galatians 6:8).
Living under grace is the marvelous alternative. If you believe the gospel – part of which includes that you died with Christ and are thus dead to sin (Romans 6:6-7) and that His perfect, unchangeable righteousness has been imputed to you (Hebrews 10:14) – then sin not only will not, it cannot rule over you!
Law can only condemn sinful human beings; grace liberates. Law aggravates sinful desires; grace grants a person the forgiveness they need as they grow into full acceptance, by faith, of a reality that existed from the moment they were regenerated: they died with Jesus to sin and rose with Him to new life, and they are perfectly righteous (justified) before God. God’s great love and grace toward His children, bringing forth a love of their own in return (1 John 4:19), are the highest motivators to resist temptation (James 1:12), flee from sin (2 Timothy 2:19-22), and cast away transgression (Ezekiel 18:30-31).