The Blood of Christ…
The blood of Christ can save us from death:
For if the blood of goats and bulls and the sprinkling of a heifer’s ashes can sanctify those who are defiled so that their flesh is cleansed, how much more will the blood of Christ, who through the eternal spirit offered himself unblemished to God, cleanse our consciences from dead works to worship the living God. For this reason he is mediator of a new covenant: since a death has taken place for deliverance from transgressions under the first covenant, those who are called may receive the promised eternal inheritance. -Hebrews 9:13-15 NAB
When someone came into contact with a dead person, a corpse, they were ritually cleansed in Jewish tradition by the ashes of a heifer mixed with water (thanks, Wikipedia). This ritual was meant to purify them and protect them from death.
Reference to this ritual can be found in Numbers 19, and the red heifer is specifically mentioned in Numbers 19:2. The rest of that chapter details exactly how the ritual should take place and is a good reference for understanding the meaning here.
The author of Hebrews is comparing the blood of Christ to the ashes of the heifer. If the ritual cleansing by a heifer’s ashes could protect a man from death, Christ’s blood could certainly do a lot more.
The blood of Christ ritually cleanses us from the death brought on by our sins. By conquering death, He gives us new life. Without it, our sins and transgressions would separate us from God forever, and we would know the full sting of death.
Like the red heifer that had to be perfect and unblemished, Christ came as the unblemished Lamb, offering His blood as a sacrifice. Once again, the New Covenant completes and supercedes the Old as Christ gave mankind a new beginning.
The blood of Christ can wash away our stains and protect us from death, as we learn in Romans 6:23 (NAB): “For the wages of sin is death, but the gift of God is eternal life in Christ Jesus our Lord.”