And almost all things are by the law purged with blood; and without shedding of blood is no remission.
Adam & Eve sinned by eating the fruit of the tree of knowledge of good and evil. Humanity arrogates unto ourselves something that is not our right – to decide what is right and wrong. This is Pride – taking something that does not belong to us, and God our creator forbade us from doing, but we did it anyway.
God requires a blood sacrifice because it imposes upon us the grim reality of the choice at hand:
Deuteronomy Deu 30:19
I call heaven and earth to witness against you today, that I have set before you life and death, blessing and curse. Therefore choose life, that you and your offspring may live,
Why did Jesus have to die?
Because He knew this, He chose death for Himself – He could easily have avoided it – yet for our sakes He took upon Himself the sin of Adam, and thereby all of our sins, so that we could live:
Catholics recall Jesus sacrifice routinely at a service called the Mass. This includes a retelling of the Last Supper, and maintain the belief that Jesus transforms the bread and wine at the alter into his Body and Blood.
“Lord, I am not worthy”
When you behold the Lord immolated and lying on the altar, and the priest standing over the sacrifice and praying, and all the people purpled by that precious blood, do you imagine that you are still on earth among men, and not rather rapt in heaven? And casting away all worldly thoughts from your mind, do you not contemplate with a clean heart and pure mind the things of heaven? O miracle! O goodness of God! He that sits above with the Father…gives himself to all who desire to embrace and receive him. At that moment all do this with the eyes of faith.
Do these things seem to you deserving of contempt, or of such a nature that anyone could despise them? Do you want to learn from another miracle the excellence of that holiness? Picture to yourself Elijah, and the immense multitude standing around, and the victim laid on the altar, and all in stillness and deep silence, while the prophet alone prays; and the fire forthwith descends from heaven upon the altar (1 Kgs 18). All this is wonderful and awe-inspiring.
Pass from then to the sacrifice which is now offered, and you will behold what is not only wonderful, but what exceeds all admiration. For the priest stands bringing down not fire, but the Holy Spirit, and he prays long not that fire may descend from heaven and consume the oblation, but that grace may descend upon the victim, and through it inflame the souls of all and render them brighter than fire-tried silver.
Saint John Chrysostom
Saint John Chrysostom († 407), Archbishop of Constantinople, was a famed preacher and commentator on Scripture. / From Glimpses of the Church Fathers: Selections from the Writings of the Fathers of the Church, Claire Russell, Ed. © 1994, Scepter Publishers, Inc. www.scepterpublishers.org.