The Day of Atonement was the most sacred day of the year for the Israelites. It was on that day that the High Priest entered the Holy Place/Most Holy Place/Holy of Holies and made an annual sacrifice for the sins of the people. In that ritual is seen the beginning of what would ultimately be culminated in the death of the Lamb of God that would take away man’s sins. Unlike the Day of Atonement which occurred every year, the death of Christ was a one-time occurrence for all time.
It was necessary for the High Priest to offer a sacrifice for his own sins before sacrificing for the people. The atonement was complete after the scapegoat bearing the sins of the people was sent away into the wilderness. Many years later, Jesus, like the scapegoat who had no sins of His own, bore the sins of all mankind.
The Israelites were forbidden from offering sacrifices at any location other than at the tabernacle. Otherwise, it could become easy to follow the practice of worshipping demons, which was strictly forbidden.
Blood is prominent in the worship of God. It was used extensively in the tabernacle worship. Years later, it is the blood of Christ on the cross that saves mankind from his sins. The importance of blood is derived from the fact that, “The life of the flesh is in the blood.”
God’s people were strictly forbidden from eating blood—even from eating meat that had not been properly bled. A person who violated that rule was to be cut off from his people. If, however, a person who had eaten an animal that had not been properly bled, washed himself and his clothes, he would be clean that evening.