He has showed you, O man, what is good. And what does the Lord require of you? To act justly and to love mercy and to walk humbly with you God. Micah 6:8
Periodically, somebody comes up with a brand new religion or philosophy or theory of ethics they claim is “ground-breaking” or “revolutionary”. But trying to come up with a truly “new morality” is pretty much like trying to come up with a new primary color.
It’s like the king in Dr. Seuss’ ‘Bartholomew and the Ooblek’. He, fool that he was, grew tired of the same rain, sun and snow coming down out of the sky and commanded the court magicians to make something new come down. Result: they summon “ooblek” which is some kind of green goo that falls and gums up everything. Finally, the King gets a clue and realizes that change is not the only good and that “radical change” can often be a prelude to disaster.
In morality, it is the same thing. There can be moral growth and improvement (as there was in the development from the Old Testament morality of “Love your friend and hate your enemy” to the New Testament command to “Love your enemy.”) But we cannot reject the very basis of morality without catastrophe. It is one thing to grow from the simple justice of the Old Testament toward the charity which commands “Love your enemy” in the New Testament. It is another things to propose hating everybody including your friends simply because it’s a novelty.
That is why the New Testament builds on, but never rebuts the moral teaching of the Old. The basic, no-brainer teaching of the Old Testament remains true everywhere and at all times: do justice, love kindness, walk humbly with your God. No dimestore philosopher on a talk show has ever built a better foundation for life than that. No one ever will.