In some societies, social conventions play a large part in what is acceptable and what must be shunned. I lived in Japan for six years, a country where pagan religions and culture represent the norm. Yet, Japanese has a very strong moral code, a sense of shame, contrition, the sense of right and wrong, etc.
If you asked them why some things are "good' and some "not good" they will usually site a social convention rather than the Ten Commandments.
So I take it from your statement that you say moral standards are conventional. Then I will ask you if there is absolute moral evil in the world? Please explain your position.
Such examples as the Japanese et al
could be reasonably argued as an example of
God’s imprint of His nature and priorities on all creation . . . at least as represented in this sphere.
Not as finitely articulated in any detailed ways as in Scripture . . . yet, recognizably imprinted.
Virtually all cultures construe it important to be loving and supportive of one’s family.
That betrayal of one’s own is horrifically bad.
That soiling one’s own nest is at least stupid, insane and/or evil.
That kindness, love, caring, compassion—at least to one’s intimates, are wise and good.
That authority lovingly, caringly, responsibly administered is better than destructive murderous chaos and anarchy.
That glorifying, exalting in death, destruction, suffering is extremely evil, stupid and/or insane.
That denying such basic minimal ‘universal’ moral values is an example of supreme ignorance if not of stupidity, insanity and/or evil.