Blood sacrifice is the kind of things horror movies are made of, right? The only visions we see of blood sacrifice are in association with cults and Satanic rituals. Since we have been talking about the Garden of Eden, let me pick up where we have left off, after the fall.
We know that when Adam and Eve sinned, they realized they were naked. I believe it is because the glory of the Lord no longer covered them, they were ashamed and tried to hide and cover themselves with leaves. They were trying to cover their sin; yet mere leaves and their own efforts could not protect them from what they would face.
The Bible says that God himself killed an animal and fashioned clothing for them, thus the blood covered their sins. A sacrifice of blood covered their sins, but did not restore the glory to them. They were still alive, but no longer had fellowship with the Lord. Their sin had caused death.
Between Eden and the cross, the Lord instructed His people to sacrifice animals as an atonement for their sins. The Old Testament rituals were very important because it was a legal and spiritual act that the priests were performing, but it was imperfect and had to be repeated over and over and over again. We see that in the garden, the sin was covered but the glory was not restored; we were still cut off from God.
In God's perfect way, He provided the sacrifice. A perfect man, fully God and fully man - for He longed to have fellowship with His creation. He longed to walk with you in the cool of the day. So He came to the Earth, he lived this painful life of a man in a fallen and hurting world. He allowed himself to be beaten, scourged, and crucified that each precious drop of blood was to restore you to the Father.
Through Christ we have communion and fellowship with God, we are covered by His blood, and He had given us back our lost glory.