Why this talk about blood?
It is written that the wages of sin is death. Death results from loss of blood and since blood is life, blood is required as a punishment for sin. Therefore blood MUST be shed as punishment for sin. There can be no peace with God until the payment for sin, blood, is shed. The Bible says that God is merciful and has allowed a substitute payment for sin. The book of Leviticus establishes the principle of substitutionary death as payment and judgment for sin.
"For the life of the flesh is in the blood, and I have given it for you on the altar to make atonement for your souls, for it is the blood that makes atonement by the life" Leviticus 17:11
In addition, the blood of a clean animal without disease or blemish was the only acceptable sacrifice for sin (Leviticus 4-6). Leviticus also demonstrates that animal sacrifice was temporary. It had to be done constantly.
When Jesus died upon the cross the veil in the temple was torn in two from top to bottom. (Matt 27:51) The veil was a curtain three inches thick that hung from ceiling to floor in the Holy Place in Herod's temple. The veil separated the Holy of Holies, where God sat on the mercy seat(*), from the eastern half of the Holy Place. Prior to Jesus' death only the high priest could enter into the Holy of Holies and then only once a year. The split veil at the exact moment of Jesus' death upon the cross signified God's acceptance of a permanent death in blood. The separation between God and His people ended with the shed blood of Jesus. But one more thing was required........
Leviticus' law of sacrifice required the people to come to the tabernacle (and later the temple) to offer sacrifice for their sin. That part did not change. Sinners are still required to come to the mercy seat(*)/the cross to ask forgiveness. Because the blood of Jesus has been accepted by God, our repentance will result in removal of guilt for sin. We are justified by the blood of Christ if we come to God and ask.
Therefore, the cross is for us - the blood is for God.
(*) Has the reader heard about the Ark of the Covenant? The Ark was a box of acacia wood and was placed inside the Holy of Holies. The wooden box was covered with gold. Several items were kept inside the box - the ten commandments, Aaron's rod and a collection of manna in a jar. The Mercy Seat was the lid and was solid gold. God was said to sit upon the mercy seat to make judgment upon the people. Original documents suggested that 2 covering angels stood next to the Ark, one on each side. Later legends placed the angels on top of the box, but that is inaccurate since God's place was on the Mercy Seat, not the angels.
We know the name of one of the covering angels and we don't know the name of the second one. One of the covering angels was named Lucifer......but that is the subject of another post.
Hope this helps.