Therefore he is the mediator of a new covenant, so that those who are called may receive the promised eternal inheritance, since a death has occurred that redeems them from the transgressions committed under the first covenant.
Jesus began a new covenant between God and humanity, one that does so much more than temporarily atone for sin through obedience and animal sacrifice. His new covenant secures an eternal home for those who believe and are His. His new covenant redeems us from sin because it was secured by His own blood.
The text proclaims Jesus as the mediator of this new covenant. He is the "go-between". And on the cross, the God-man gave His life so that humanity could find peace with God, deliverance from His wrath on sin, forgiveness, and eternal life. The blood of Jesus' own life sacrifice secured all this for His people eternally.
Jesus did this knowingly and willingly. He knew the sinner I am. He knew my transgressions of God's perfect law because He died for every one of them. And He secured for me what no priest or temple ritual ever could: full redemption from sin's penalty of death, pardon for my sin before the Father, and everlasting life!