“For the life of the flesh is in the blood, and I have given it to you upon the altar to make atonement for your souls; for it is the blood that makes atonement for the soul.” (v.11)
God agreed here that there was spiritual significance in the blood of an animal or person. The difference was that among pagans, they said: “The life is in the blood; I must eat or drink it and take that life for myself.” The godly Israelite said, “The life of the flesh is in the blood, and it therefore belongs to God and not to me.” This emphasized a powerful idea: life belongs to God. God sets His face against that person who takes authority over life for themselves. Life depends on blood, is preserved by blood, and is nourished by blood. When enough blood leaves a body, life leaves a body.
Additionally blood was the means by which atonement was made, and God stipulated that the blood of an innocent lamb could atone for sin. When Jesus Christ began his ministry, He was introduced (by John the Baptist) not as the Prince of Peace or the Messiah of Old, but as the "Lamb of God who takes away the sins of the world."
The Passover Lamb of Exodus 12 was a prophetic, divinely-appointed foreshadowing - a type of the coming Christ. And when Jesus Christ died, the life-giving blood drained from his body, providing forgiveness and eternal life to all who believe. Thus making atonement possible for all mankind with one sacrifice.
The Truth: “Knowing that you were not redeemed with perishable things like silver or gold from your futile way of life inherited from your forefathers, but with precious blood, as of a lamb unblemished and spotless, the blood of Christ.” (1 Peter 1:18-19)