The gospel of Christ is God’s final and for all covenant with man. After speaking specifically of the need to change the law (7:12), it seems the author wants to reassure his readers that the new covenant isn’t totally unrelated to the former.
Continuing his discussion of the high priesthood, I cannot help but think of the dilemma facing the Jews of that day. The high priesthood had become diminished and tarnished by the politics of the Idumeans and their interference in the religious affairs of the people. The thought of a sympathetic, undefiled and eternal high priest should have been music to the ears of the people.
Our author moves to the superiority of the covenant of Christ over that of Moses. First and foremost, the covenant of Christ is superior because it was established on better promises than Moses’ covenant. This promise is then identified as the forgiveness of sins. As we will see in chapters 9 and 10, the law of Moses did not offer forgiveness of sins in the complete and fullest sense of the word, because “it is not possible for the blood of bulls and goats to take away sins” (Heb 10:4).
The covenant of Christ brought full and absolute forgiveness to its adherents. Moreover, the former covenant foretold of its own demise through the establishment of the new covenant. The author quotes Jeremiah 31:31-34 and applies it to the covenant of Jesus. With this new covenant, there is no longer the remembrance of sin as with the first covenant (cf 10:3).
Finally, as is the case with any testament or will, the most recent document replaces and supersedes any former one. By the time Hebrews was penned, much of the Jewish world had heard the gospel of Jesus Christ. As the scope of the gospel of Christ increased in its proclamation, the validity of the Mosaic covenant waned at the exact same rate. Once the gospel was preached to the whole world, the law of Moses was finished.
The gospel was preached to the whole world within 30 years of the establishment of the church in Acts 2 (cf Col 1:6, 23). God marked this completion with judgment upon Israel and Jerusalem’s destruction, just as Jesus foretold (cf Matt 24:14).
That which was becoming obsolete in that day is long since been done away with. Nothing of it remains for us today aside from education (cf Rom 15:4).