Justification of Sin vs. Justification of the Sinner

Dietrich Bonhoeffer used this phrase in his book, "The Cost of Discipleship." I struggled for some time to understand what he meant in this phrase as he compared cheap grace to costly grace. What he means is that cheap grace only covers the sin. It is only concerned with the sin. It does not concern itself with the very being of the person, the sin nature that is buried deep inside of us resulting from original sin. Cheap grace says "we are all sinners -- we will always sin -- there is nothing that can be done about it -- but God has forgiven our sins. So, don't worry about changing your life and repenting of your sins because there is nothing you can do to change. Keep sinning and keep trusting in God to forgive your sins through the blood of Jesus."

Costly grace, on the other hand, concerns itself not so much with individual sin (although it does take care of that), but with the sin nature of the person. Costly grace justifies the sinner. It removes the sin nature. When Christ died on the cross, He did not die to gain victory over sin. He died to gain victory over the sinful nature in humans. Costly grace says, "You no longer have to live the way you did before. The sinful nature has been defeated by the blood of Jesus. Yes, you will continue to sin, but as you grow and as you trust in the grace of the Lord Jesus Christ to change your very nature, you will sin less and less. The goal is to change you from the inside out -- not merely to white-wash the outside."