BLOODSHED
Genesis 9:5 "Surely for your lifeblood I will demand a reckoning; from the hand of every beast I will require it, and from the hand of man. From the hand of every man's brother I will require the life of man. 6 "Whoever sheds man's blood, By man his blood shall be shed; For in the image of God He made man.
When Cain murdered Abel his brother, God did not at that time impose the death penalty, but instead God put a mark on Cain and sentenced him to a life in exile. Because murder was a new thing in the world, Cain would become a living object lesson. Through Cain and his descendants God would let humanity see just how evil a thing a disregard for human life really is. The result was a world where life was cheap, a world filled with violence. God now imposes the death penalty for murder. This is the first time God has committed the execution of such a harsh penalty to man - the most extreme punishment man is capable of delivering. By this God shows just how serious in His sight the murder of another is.
But there is something else here too. God is not saying “if�?but “when�?it happens. Blood will be shed. As has already been shown, the flood did nothing to change the fundamental character of fallen man. And in the course of time, the world would once again be filled with violence, life would once again be cheap. The implementation of the death penalty would often be grossly abused, nevertheless, God in His wisdom knew what He was doing. The imposition of this penalty, however imperfectly, would serve to some degree as a restraint on the wicked, and serve to help keep civil order in society, at least for a time.