I think you are misunderstanding what I wrote above. May I suggest you read post #139 again?Yes, the law is holy, just and good. That does not mean the law was meant to save man. In fact, Paul tells us just how wrong this type of conclusion really is. Instead, Paul tells us that the Law was meant to magnify sin.
How does it do this? Because the "Law is holy, and the commandment is holy and just and good" and men are not.
Is there a reason that you believe the law that God gave to Adam in the form of a commandment, one he transgressed, served a different purpose than the Law God gave to Israel, the one they transgressed?
After the Fall the moral law has three uses:
1. To restrain sin (to some degree) in the unregenerate (Romans 2:14-15) .
2. To convict men of sin and cause them to look for salvation (Romans 3:20; 7:7)..
3. As a rule of life for the saved (Romans 6:12-16)..
This is explained in more detail in the 1689 confession, Art XIX.