Was then that which is good made death unto me? God forbid. But sin, that it might appear sin, working death in me by that which is good; that sin by the commandment might become exceeding sinful.
Paul asked the question “did the Law become death to me?”, which means is the Law the culprit that brings death to all sinners. Paul answered the question with certainty that it was not the Law which was the problem, but sin. The Law did not begin sin, but it showed sin in all its exceedingly sinfulness. Our fallen human nature instinctively wants to do whatever is forbidden. So it uses the Law to awaken otherwise dormant lusts in the sinner’s life. The more he tried, the worse it got, till at last Paul was brought to despair of all hope. Thus sin used the Law to cause any hope of improvement to die in him. And he saw the exceeding sinfulness of his old nature as he never saw it before.