Deuteronomy 12:24

Thou shalt not eat it; thou shalt pour it upon the earth as water.

The verse belongs to the law Moses recalled to Israel before they crossed the Jordan as sacred instruction they were solemnly charged to keep. It commands that blood must not be eaten but poured out on the ground like water, so animals must be thoroughly bled before their meat is eaten and the blood covered with dust. Blood must not be eaten because it represents the life of the flesh. In the sacrificial service the life poured out at the altar stood for the sinner's life transferred to the offering and offered in place of the repentant sinner's life.

Blood is required for atonement because the law's penalty for sin is death. The life poured out at the altar pointed to the life of the spotless Lamb who would take away sin. Christ did not keep his life for himself but poured it out freely for humanity, making it possible for people to give their lives to God.