system
A chat on subreddit /r/PoliticalCompassMemes
human
I'd say it's down to the fact that certain truths are universal whether inside or outside of religion, and across multiple religions. 

Murder is bad, theft is bad, even affairs are frowned upon even if they aren't illegal. Most of these laws exist across cultures even before cultures started to meet and trade.
gpt
It's not that they are universal, it's more that if some culture was ok with murder it probably went extinct rather quickly. Natural selection.