Blessed are the pure in heart;
For they shall see the Lord.
(Matthew 5:8)
Legalism merely forbids the sinful act. But this traps the sinner's focus upon the very sin he hopes to avoid. And this is a deadly error for "the mind which is set on the flesh is death" (Romans 8:6).
It leads to obsession with the act rather than freedom from it. Afterall, "the law came that sin may abound" (Romans 5:20) and we can be sure that it will. Freedom is not found by that way - slavery is, greater sin is. The outcome of a legal attitude toward sin is not freedom at all but addiction, obsession and an abounding of still greater sin. It is no wonder fundamentalist and legalist movements produce so many obsessed, addicted and corrupt leaders. We must say with Paul to these leaders, "teacher teach yourself" (Romans 2:21)
In place of the law alone, we must command adoration of God. Teach what it is and how it is done. Allow weary souls, particularly our own weary souls, to wonder at God and the glory of His love for us. Allow a genuine love for God to be kindled within these weary souls. Show how He may be had and how He may be enjoyed. Show forth to weary souls the goodness of knowing the Lord. And then show how the sinful act destroys our fellowship with Him, and uproots our knowledge of Him. Then will the sinner say in his heart, "The law of the Lord is better than silver and gold..." (Psalm 119:72)
This is the foundation of true repentance for so long as mere holiness is our goal we will find only greater corruption. But when having and knowing God Himself becomes our goal, we will have Him and great repentance as well.