According to his design, the Lord had set the blood of an animal apart to atone for human sin. In this way, the blood was both sacred and substitutionary. It could not to be consumed in a common way. Animal blood was limited to the sacrificial system of Israel. According to Ross, draining blood from an animal formed a graphic picture for the worshiper that the lifeblood was taken. God had designed it this way so that the people were confronted with the loss of life and reminded of the sacrifice every time the blood of an animal was shed.
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11 For the life of the flesh is in the blood, and I have given it for you on the altar to make atonement for your souls, for it is the blood that makes atonement by the life.