Our concept of good and evil cannot be something decreed to us externally by God. If our notion of right and wrong were given to us by God and known to us only through scripture, then it would never occur to us to distinguish a scriptural prohibition against murder from one against eating blood sausages (as the Europeans are wont to do and which is _consistently_ condemned in the Western scriptures). That we dare to make such distinctions is ample proof that our knowledge of good and evil is independent of scriptural revelation.
The diversity in the specifics of good and evil in the world is no argument against the internal origin of our moral conceptions. This diversity is based on only two things: our understanding of what is helpful and hurtful, and our recognition of friend and foe. And so it is universally good to help a friend and evil to hurt him or her. Once the notion of friend is expanded to include all persons, and once agreement arises on what is helpful and hurtful in given situations, universal agreement on the specifics of right and wrong will also arise.
And so even though our moral conception of right and wrong might arise within each of us, the final result is not chaos but perfect agreement. Hence there is no reason to think that Jesus in his commentary about the Golden Rule did not mean his words very seriously, namely: it is the law and the prophets, i.e., it is all that God might ever require of any person.*
[* This last paragraph was deleted in its publication in the 12/16/00 Atlanta Journal/Constitution Faith and Values section.]