"...He is the mediator if a new covenant."
"...without the shedding of blood there is no forgiveness."
You may read the whole passage, but between these two verse is the crux of it.
Adam Clarke says, "The new contract (covenant) betwixt God and the whole human race, by Christ Jesus the Mediator distinguished here from the old covenant between God and the Israelites, in which Moses was the mediator. 'For the redemption of the transgressions' To make atonement for the transgressions which were committed under the old covenant, which the blood of bulls and calves could not do; so the death of Jesus had respect to all the time antecedent to it, as well as to all the time afterward till the conclusion of the world."
Wow, did you catch that? Our Mediator stretches from the beginning to the end. All those who sought forgiveness under the sacrifices of the old covenant were covered by the sacrifice of Christ in approximately 30 A.D. Now in 2017 it is still effective and will continue to be so until the end of time. But you see, God is outside of time. Time itself is His creation. He is the Alpha and Omega, the Beginning and the End, but in eternity our time stops and His goes on forever.
We always seem to go back to the Garden, don't we? The curse for Adam's disobedience was death. The first blood ever shed since the creation of the world was for a covering, a skin, for Adam and Eve in order to cover their nakedness. It was shed by God's own hand. I'm guessing it was a lamb, but I don't know. It was probably shocking to Adam and Eve as they stood there watching, quaking in their boots--oh, yeah, they didn't have boots. Even so, they saw death exhibited for them. Sadly, the first human death was Cain killing Able, the first two sons of Adam and Eve, one murdering the other. Now they really got it, what death meant. Able's blood cried out to God from the ground upon which it spilled.
Andrew Murray says, "All the transgressions of the old covenant had been treasured up; the death of Christ gave satisfaction to all that that covenant could claim, and brought release. So the Mediator of the new covenant begins an entirely new economy, with sin put away by the sacrifice of Himself...We all understand how absolutely a last will and testament needs a death. As sure as the death of a maker of a testament puts the heir in complete possession of the promises, so surely has the death of the Mediator make a perfect redemption from all transgression."
"'They which are called' The Gentiles, 'might receive the promise'--might, by being brought into a covenant with God, have an equal right with the Jews...to an eternal inheritance...they were called and elected in the place of the Jews, the ancient called and elect, who were now divorced and reprobated because of their disobedience."
"A victim was required for the ratification of every covenant"
While teaching a children's Sunday School class while in college, one of the first grade bus kids asked me to stop talking about the meaning of Easter. He put his hand on his forehead and said, "All they talk about is blood, and it gives me a headache."
However, when I taught in a Christian preschool, I must admit that I was a little partial to a darling red-head three year old Joshua. When we talked about the meaning of Easter, I had them lay on the floor to make the shape of the cross. He said while lying there, "I would die for you, Miss Celia." Oh such love, even from the mouth of babes!
Andrew Murray reminds us, "The life is in the blood. The blood shed is the token of death, life taken away. Death is always and everywhere God's judgment upon sin: 'The sting of death' is sin.
"Our Lord refers to the conduct of Moses (sacrifices and sprinkling of blood), and partly quotes his words in the institution of the eucharist: 'This is My blood of the new covenant, which is shed for many for the remission of sins (Matthew 26:28)...He gave His life for the life of the world; human life for human life, but a life infinitely dignified by its union with God." (Adam Clarke)
Steinhofer says, "One drop of that blood, sprinkled out of the sanctuary on the heart, changes the whole heart, perfects the conscience, sanctifies the soul, makes the garments clean and white, so that we are meet for fellowship with God, ready and able to live in His love. Such a heart, sprinkled and cleansed with the blood of Jesus, is now fitted for the grace of the new covenant, all the heavenly gifts, all the holy operations of divine love, all the spiritual blessings of the heavenly places. The blood of the Lamb does indeed make the sinner pure and holy, worthy and fit to partake of all that the inner sanctuary contains, and to live in God. Therefore the apostle says: 'Let us, as those whose hearts are sprinkled from an evil conscience, boldly draw near before the face of God.'"
Woe to those who discount the power of the blood to cleanse and purify a heart, discounting the very blood shed by our Savior and the whole intent of His coming.