John Adams said, “Our constitution was made only for a moral and religious people. It is wholly inadequate to the government of any other.”
Agreed.
In the absence of such, one cannot explain or provide a reasoned response to why an unjustified killing of another should be “illegal,” for example.
In the absence of an external source of limits on man’s behavior, the legality of any behavior becomes debatable.
If it is debateable, it is therefore debateably permissible.
“Enh, John Adams was a fatso, and a cold and distant father.”