Why is blood so significant?
When apostle Paul is speaking to the church leaders in Ephesus he refers to how God 'obtained' the church, i.e. saved it and brought it into existence, "with the blood of His own Son". Paul puts emphasis on the blood:
Take heed to yourselves and to all the flock, in which the Holy Spirit has made you overseers, to care for the church of God which he obtained with the blood of his own Son. Acts 20:28 (RSV)
But why does blood matter? Why does God ask us to focus on the blood of Jesus and why was the blood of the sacrificed animals so important? The answer is that to God, blood represents life. Indeed, the Bible says that the life of every creature is contained within its blood:
For the life of the flesh is in the blood; and I have given it for you upon the altar to make atonement for your souls; for it is the blood that makes atonement, by reason of the life. Leviticus 17:11 (RSV)
For us to be forgiven and to avoid God's punishmen for our sint, somebody has to lay down their life in our place. The laying down of that life is represented by the shedding of blood. So, Jesus' death is essential for us to be saved. That death also had to involve the shedding of His own blood for us. The blood of Jesus has real power to save us. If He had not shed His blood for us, there could be no forgiveness:
And according to the Law, one may almost say, all things are cleansed with blood, and without shedding of blood there is no forgiveness. Hebrews 9:22 (NASB)
In the Old Testament, there could be no forgiveness unless the sacrificed animals shed their blood. But they were really only a temporary symbol or illustration which pointed towards the blood that really counts. That is the blood of Jesus, without which none of us can be saved.
The laying down of Jesus' life on our behalf was essential for our salvation. Moreover, His death had to involve the shedding of His blood. His execution could not have been done by some other means, such as hanging, which would not have involved the shedding of His blood.
These passages above from Exodus and Leviticus tell the Jewish people how to get their sins temporarily dealt with or 'covered for', by the death of lambs, goats and bulls. They also point forward to the completely effective and permanent sacrifice of Jesus. That was how our sin problem was to be dealt with once and for all. The passages above relate to the daily sacrifices in the part of the Temple known as 'the Holy Place'. However, the most well known reference to the word atonement is within the phrase 'the Day of Atonement' or 'Yom Kippur'. This is the most important day of all the Jewish feast days.