The law has many purposes. It reveals much about God. It restrains sin. It also preserved Israel from destruction until Messiah.
Did anyone need to tell Cain that murder was wrong? Did God need the law to pass judgment on all mankind?
And knowing what is wrong doesn't empower one to do right. The law convicts. It also leads one to Christ.
I was talking about the part of the Law that you should know about.... And, you did.
I did not ask for a dissertation about the various aspects of the Law that does not pertain to the aspect I was pointing to.
You just wander....