After the fall, God clothed Adam and Eve in tunics of skin (Gen. 3:21). These leather tunics indicate that a blood sacrifice was offered as a ransom for human sin, standing in place of Adam and Eve in receiving the sentence of death, and covering their nakedness. Subsequently, each generation learnt from the generation before it to offer blood sacrifices, so that it is rare to find a religion whose rites do not include the shedding of blood. Through the generations, this idea sometimes became corrupted — some even came to sacrifice their own children.
678 Origen, Homilies on Jeremiah 18.6(7) (FOTC 97:200–201).
In the fullness of time, humanity received the written law from Moses’s hands, which law required blood sacrifices because “without the shedding of blood there is no remission” (Heb. 9:22). Blood sanctifies all; and without it, nothing and no one — even if he be high priest — can be sanctified to the Lord: “For when Moses had spoken every precept to all the people according to the law, he took the blood of calves and goats, with water, scarlet wool, and hyssop, and sprinkled both the book itself and all the people, saying, ‘This is the blood of the covenant which God has commanded you.’ Then likewise he sprinkled with blood both the tabernacle and all the vessels of the ministry. And according to the law almost all things are purified with blood, and without shedding of blood there is no remission” (Heb. 9:19– 22).