The theme of blood linked to that of the Paschal Lamb is of primary importance in sacred Scripture. In the Old Testament the sprinkling of the blood of sacrificed animals represented and established the covenant between God and the people, as one reads in the Book of Exodus: "Then Moses took the blood and sprinkled it on the people saying: ‘This is the blood of the covenant that the Lord has made with you on the basis of all these words of his'" (Exodus 24:8).
Jesus explicitly repeats this formula at the Last Supper, when, offering the chalice to his disciples, he says: "This is my blood of the covenant, which will be shed on behalf of many for the forgiveness of sins" (Matthew 26:28). And, from the scourging, to the piercing of his side after his death on the cross, Christ has really shed all of his blood as the true Lamb immolated for universal redemption. The salvific value of his blood is expressively affirmed in many passages of the New Testament.
In this Year for Priests, one need only cite the beautiful lines of the Letter to the Hebrews: "Christ ... entered once for all into the sanctuary, not with the blood of goats and calves but with his own blood, thus obtaining eternal redemption. For if the blood of goats and bulls and the sprinkling of a heifer's ashes can sanctify those who are defiled so that their flesh is cleansed, how much more will the blood of Christ, who through the eternal spirit offered himself unblemished to God, cleanse our consciences from dead works to worship the living God?" (9:11-14).
Dear brothers, it is written in Genesis that the blood of Abel, killed by his brother Cain, cried out to God from the earth (cf. 4:10). And, unfortunately, today as yesterday, this cry does not cease, since human blood continues to run because of violence, injustice and hatred. When will men learn that life is sacred and belongs to God alone? When will men understand that we are all brothers? To the cry of the blood that goes up from many parts of the earth, God answers with the blood of his Son, who gave his life for us. Christ did not answer evil with evil, but with good, with his infinite love. The blood of Christ is the pledge of the faithful love of God for humanity. Looking upon the wounds of the Crucified, every man, even in conditions of extreme moral misery, can say: God has not abandoned me, he loves me, he gave his life for me -- and in this way rediscover hope. May the Virgin Mary, who beneath the cross, together with the apostle John, witnessed the testament of Jesus' blood, help us to rediscover the inestimable riches of this grace, and to feel profound and perennial gratitude for it.
(Pope Benedict XVI)