I heard a sermon about this when I was in college. There are civilizations in the world where this kind of thing happens, and it’s just life to them. The difference between them and us seemed to be that their civilizations never had been touched by the Gospel.
The common denominator among the civilizations where murder, and other crimes, are considered crimes is that at some point in their history they had been exposed to the Gospel. It’s there basis for a moral compass.
I don’t know if that’s true, but it made sense when examples were given.
Atheists are very upset when you point out how much of our decency has Judeo-Christian roots; Mother Theresa shamed Hinduism by caring for those India had determined had “bad karma”...