Why is blood the means God uses to bring new life?
God sovereignly mandated that forgiveness and redemption come only through shed blood. Blood is the means because life is in the blood, and new life cannot come until death occurs; life emerges from the death of a previous life, which is pictured in death, burial, and resurrection.
Les explains that God, in His sovereign way of doing things, decided that it would be through the shed blood that He would forgive sin and no other way, and this must be taken by faith. His personal idea why God chose the blood is because life is in the blood, and you cannot have new life until death takes place, and life again comes out of that death of a previous life. That is what the death, burial, and resurrection is all about. God has therefore mandated that there can be no salvation and no forgiveness without the shedding of blood. In Ephesians 1:7, believers have redemption through His blood and the forgiveness of sins according to His grace, not according to what we deserve.
In whom we have redemption through his blood, the forgiveness of sins, according to the riches of his grace;