It is clear from reading the Gospels that the disciples found it hard to believe that the Mediator of the new covenant would have to die (for example, Mark 8:31–32). They knew that a new covenant was coming, but they were more focused on its earthly power than on what would be necessary for the covenant to be ratified.
Many others who lived during the first century found it so hard to accept the necessity of Christ’s death that they denied He was the Mediator of the new covenant. No doubt they tried to use His death to convince others that Jesus was not the promised Messiah.
In chapter 9, the author of Hebrews seeks to address this problem by reminding His audience that the death of the new covenant Mediator is required to bring the new covenant’s blessings. The old covenant had sacrifices and rituals that could not perfect the conscience of the worshiper (v. 9). But the blood of Christ is not like this; in fact, it purifies the conscience for service (v. 14). And just as a death is necessary in order for a will to take effect, so too was the death of Jesus necessary for us to receive His willed inheritance (vv. 16–17).
When a covenant is made, the shedding of blood must occur. This was certainly true of the old covenant and so must also be true of the new covenant (if it is to fulfill the old one). This is the point addressed in verses 18–20. The author refers to Exodus 24:1–8, reminding us that the old covenant was inaugurated with blood. The death of the animal to atone for the sins of Israel and render the Israelites ritually clean was necessary for the old covenant to be ratified. So too a death would be required to consecrate the new covenant.
John Owen gives some helpful theological insight into the ritual here described by the author of Hebrews. “This distribution of blood, half on the altar, half on the people, one to make atonement, the other to purify or sanctify, taught the double efficacy of Christ’s blood in making atonement for sin for our justification and purifying of our natures in sanctification.” The ineffectual animal blood that Moses used ratified the old covenant and pointed to the need for effectual blood to ratify the new one. Just as blood had to be shed to dedicate the old covenant, Christ had to die to consecrate the new one. And without His death we do not have peace with God.
The death of Christ is often the biggest stumbling block for unbelievers. They cannot understand how this display of seeming weakness leads to eternal glory. But, as we have read, there is no glory without His suffering. When sharing the Gospel with unbelievers, let us not be ashamed of the atoning death of Jesus Christ.