Christians and other monotheists can point to codified moralities and draw direct lines between infractions and the actual consequences of same, and argue for the evidence that shows these morals are superior to other moralities
If a man have a stubborn and rebellious son, which will not obey the voice of his father, or the voice of his mother, and that, when they have chastened him, will not hearken unto them: then shall his father and his mother lay hold on him, and bring him out unto the elders of his city, and unto the gate of his place; and they shall say unto the elders of his city, "This our son is stubborn and rebellious, he will not obey our voice; he is a glutton, and a drunkard."
And all the men of his city shall stone him with stones, that he die: so shalt thou put evil away from among you; and all Israel shall hear, and fear.
Yeah, I have trouble with the idea of moral supremacy. You can keep it, thanks.