The nature of sin was defined in the Garden of Eden.
When Yahweh confronted Adam, the response of Adam was to bear false witness against Yahweh and Eve who Yahweh had Graciously given to Adam. No snake was accused.
Bearing false witness has been the attribute of wicked folks ever since. Adam was the sly & subtle beast in the Garden of Eden.
Adam's genetic code recorded his treachery, and this was implanted in Adam's first kid, Cain. When Cain was irritated by Abel, Yahweh told Cain to drop his anger.
Cain did exactly what Adam did; Cain did what he wanted to do, thus usurping in his mind the place of Yahweh to decide good & evil. So, ignoring He with Perfect Knowledge, is a rebellion and mental murder of the Perfect Man, YahwehShua who can save us, if we let Him.