And surely, I will require your blood for their lives, from the hand of every living thing I will require it. And from the hand of man, the hand of each of his brothers, I will require the life of the man. The one pouring out the blood of man, by man his blood will be poured out, because the man was made in the image of God (Genesis 9:5–6).
God has added all animals that move upon the earth, the fish of the sea, and the birds of the air to the diet of a human. The fear of man will be upon these animals, and they will be permitted to pour out the blood of man. Meat has now become a part of the dietary regiment of both men and beasts. Man is permitted to eat them, and they are allowed to kill men.
When it comes to a man killing another man, capital punishment is now implemented. When Cain slew his brother, God did not require his blood. He sent Cain away from His presence and from his family to be a vagabond upon the earth (Genesis 4:12). He was also marked so that anyone who found him would know that they are not permitted to kill him (Genesis 4:14). In the first world system, this standard was manipulated to justify killing a man without repercussions (Genesis 4:23–24). Men used this principle to justify their wickedness, producing an environment of violence (Genesis 6:11).
With these instructions, God is implementing the dispensation of government. Mankind is now responsible for managing himself, and thus required to take the life of a man who kills another man. Man was made in the image of God, and now he is to respond in a proper manner towards a man who kills another man.