In the Old Testament, as well as in the many pagan religions, blood sacrifice was offered in atonement for sin. This was a foreshadowing of the real and eternally efficacious sacrifice of the Lamb of God Who takes away the sins of the world. The Blood of the Lamb it is that neutralizes and defeats evil, cleanses us from the contagion of sin, and regenerates us into something beautiful for God.
From the series "The Blood that Saves".