Cain’s sin was to kill his brother because God had accepted Abel’s offering but not his own (Genesis 4:1–26). John compares Cain’s murderous deed to the hatred of fellow believers (1 John 3:11–15) and in Jewish communities Cain was typically considered to be the archetypical sinner.1 To walk in the way of Cain is to go along with the one who laid down the pattern of sin for humanity.2
11 Woe to them! For they walked in the way of Cain and abandoned themselves for the sake of gain to Balaam’s error and perished in Korah’s rebellion.