If there was no God what would make that true? The big fish eat the little fish - are big fish evil? God is what makes the golden rule an aspect of morality. Apart from God, might makes right and what's right is what you can get away with.
‘If there was no God what would make that true?’
I stated ‘don’t do to others what you don’t want them to do to you’; this is the very basis for natural enemies to form alliances that enable cultures and civilizations to thrive...it is a very basic and human self preservation ethic; why is it necessary to postulate a deity to provide instruction into what is,after all, basic instinct...?