When God established His people Israel He gave them His vision for what He was hoping to accomplish through them – that they would be His holy people and serve as priests to the rest of the world.
Israel would accomplish this role by completely obeying all the commands of God which He had given to His people for pleasing Him and accomplishing His will.
Israel failed to obey God’s commands, they failed to serve the world as priests of God and so God removed them from their land and replaced this plan with a new plan which He Himself would establish by His own blood.
The new agreement or new covenant established by God has the same objective and responsibilities as the old – the people are to obey God’s commands and serve Him as a kingdom of priests upon the earth.
The primary difference is that the old agreement had to be maintained by the priests perfect performance which they failed to accomplish.
The new agreement is maintained by the High Priest Jesus’ perfect accomplishment thus all those cleansed by His sacrifice now are declared permanently to be priests of God.
Jesus the High Priest perfectly obeyed God eliminating the requirement for all men to live perfectly as priests of God, something no man has ever done nor has the capacity to do.
Yet as priests of God through Jesus Christ we still are expected to obey God by the power of the Holy Spirit and to serve God by declaring peace and forgiveness of sins to the world through the work of Jesus Christ on the cross.
God still expects His people to live as priests which are to live as both a servant of God and a servant of humanity even as our High Priest Jesus the Lord did when He lived among us.