“God’s law was given so that all people could see how sinful they were.” Ro 5:20 NLT
Why did God do away with Old Testament law and institute grace? Because while the law had the power to let people know how far short they fell, it didn’t have the power to make them want to obey it. Let’s suppose you have a tendency to eat too much chocolate. You want to be free from the habit, so you make a law for yourself: “I must not eat chocolate. I cannot eat chocolate. I will never eat chocolate again.” You even convince yourself that for you it’s a sin to eat chocolate. But this self-made law doesn’t set you free from the desire for chocolate; it actually seems to increase your problem! Now all you can think about is chocolate; it’s on your mind day and night. Eventually you find yourself sneaking around to eat chocolate because you told everybody you were never going to eat it again. You can’t eat chocolate in front of people so you hide when you eat it, and end up feeling really guilty because now you’ve become a “sneaky” sinner. Now you understand the pain that comes from being “under the law” instead of free in Christ. New believers often focus their attention on God’s laws in order to control their passions, but it doesn’t work. As they mature, however, they learn to direct their attention to the leadership of the Holy Spirit, and discover that He can set you free from the desire to sin. The law requires living by willpower; living by grace requires drawing each day on the power of God’s Spirit.