What does Hebrews 8:10 mean?
In the epistle to the Hebrews the (unknown) author speaks extensively about the covenant. We don't know exactly who his addressees are: messianic Jews in Jerusalem or in Judea and Galilee, or a congregation with Christians from the Jews and Gentiles, second generation Christians around the year 80 A.D.? He indicates that they're losing hope and courage, yes also that some are in danger of leaving the faith, or falling back into the Jewish life of the old covenant. The author exhorts them to remain faithful to Christ and to find in him the full assurance of their faith and salvation. His letter is more like a sermon than an epistle, in which he includes quotes and reference to the OT. In chapter 8:1 we find the theme and main focus of his topic: in Christ we have a terrific high priest who does his daily work for us with power and glory in his heavenly sanctuary! In this central chapter of his epistle he includes the most extensive quote from the OT, the prophecy of Jeremiah in chapter 31 about the new covenant! Jeremiah's prophecy is of fundamental importance for the life of the NT church under Christ, the high priest of the new covenant. It shows the bridge God would lay across the breach Israel caused by its disobedience (8:8): a new covenant!
In Hebrews 8 the author shows that the old order was inadequate as a way of restoration of the communion with God. The Sinai covenant and the old priestly service ran stuck on the sin of God's people and were unable to accomplish the atonement and renewal necessary for this restored communion. This had become evident very much in the captivity of God's covenant nation. At that time, however, Jeremiah had comforted Israel with the promise of a new and better covenant, a covenant of atonement, forgiveness of sins, and the renewal of hearts, which will open the way to a new life in which it will apply to each and everyone of God's people, "I will be their God and they will be my people." In Hebrews 8 and 10 the author shows that this new order in the eternal covenant of God will be possible thanks to the perfect sacrifice of Christ! In other words, the old covenant refers to a period in the eternal covenant the LORD made with Abraham (the Sinai covenant till the captivity), while Jeremiah announces the coming of a new covenant, a better covenant, with a better and more powerful way of atonement, reconciliation, and renewal of heart and mind; of life and communion with God!
The author shows that Christ is the Mediator of this new covenant, who takes away the sins committed during the first covenant because the sacrifices of animals couldn't remove them (9:15); his priestly service worked retro-actively. His sacrifice is the firm foundation for this new covenant so that God will not remember the sins any longer nor sees them as covenant breakers. His sacrifice once offered at the cross is the only ground of our salvation! As Christ himself put it at the institution of the Lord's Supper, "This is the new covenant in my blood!" Paul also calls himself the apostle of the new covenant, alluding to Jeremiah 31:31 (2 Cor 3:6; cf. Rom 11:27; Jer 31: 33, 34). God abolished the old to establish the new (10:10). Christ is the bridge over which sinners may approach God with a sincere heart, in full assurance of faith, their hearts sprinkled to cleanse them from a guilty conscience and having their bodies washed with pure water (10:22).
It's this one sacrifice that lead to the outpouring of the Holy Spirit, which is the unifying truth of God's Word and the NT sacraments as well. Our baptism, administered to the believers and their seed (in accordance with the principles of the eternal covenant made with Abraham), testifies that Christ's sacrifice made an end to all shedding of blood for the atonement of our sins and the reconciliation with God, and signifies the washing away of our sins and the renewal of our life. In the Lord's Supper, also, we celebrate the new covenant in his blood, the covenant of reconciliation and renewal!
Thus we see the continuity in the covenant of grace, the progression from the old to the new covenant in Christ's blood, and the bridge to the new world, opening the way to the celebration of the communion with God on the new earth, where God's faithful covenant children will be gathered around the throne of the Lamb (Rev 22:3). That will be the fulfilment of the restoration of the communion with God.