15 Through the Spirit, Christ offered himself as an unblemished sacrifice, freeing us from all those dead-end efforts to make ourselves respectable, so that we can live all out for God. 16 Like a will that takes effect when someone dies, the new covenant was put into action at Jesus' death. His death marked the transition from the old plan to the new one, canceling the old obligations and accompanying sins, and summoning the heirs to receive the eternal inheritance that was promised them. He brought together God and his people in this new way. 17 18 Even the first plan required a death to set it in motion. 19 After Moses had read out all the terms of the plan of the law - God's "will" - he took the blood of sacrificed animals and, in a solemn ritual, sprinkled the document and the people who were its beneficiaries. 20 And then he attested its validity with the words, "This is the blood of the covenant commanded by God." 21 He did the same thing with the place of worship and its furniture. 22 Moses said to the people, "This is the blood of the covenant God has established with you." Practically everything in a will hinges on a death. That's why blood, the evidence of death, is used so much in our tradition, especially regarding forgiveness of sins.
Matthew Henry's Commentary on Hebrews 9:15-22
Commentary on Hebrews 9:15-22
(Read Hebrews 9:15-22)
The solemn transactions between God and man, are sometimes called a covenant, here a testament, which is a willing deed of a person, bestowing legacies on such persons as are described, and it only takes effect upon his death. Thus Christ died, not only to obtain the blessings of salvation for us, but to give power to the disposal of them. All, by sin, were become guilty before God, had forfeited every thing that is good; but God, willing to show the greatness of his mercy, proclaimed a covenant of grace. Nothing could be clean to a sinner, not even his religious duties; except as his guilt was done away by the death of a sacrifice, of value sufficient for that end, and unless he continually depended upon it. May we ascribe all real good works to the same all-procuring cause, and offer our spiritual sacrifices as sprinkled with Christ's blood, and so purified from their defilement.