A Royal Priesthood
In 1 Peter 2:9 Peter writes, "But you are a chosen race, a royal priesthood, a holy nation, a people for God's own possession, so that you may proclaim the excellencies of Him who has called you out of darkness into His marvelous light."
For years I always read this and simply thought it was a cool verse filled with encouraging verbiage for Christians. But I've come to find that Peter is doing much more in his choice of language than merely giving his audience a pat on the proverbial back.
The language Peter employs is filled with allusions to the Israel of the Old Covenant. Israel was called to be both salt and light to the world. Israel was a priestly nation that was called to proclaim the message of God's grace to the world. They were to image this by living holy lives that were set apart from the pagan practices of the nations around them. In his first epistle Peter is equating the mission of the church in Asia Minor to that of the mission of Israel throughout the Old Covenant.
But there is something more that we must see here as Christians. Jesus is the center of all things. Jesus is the royal priest, Jesus is the chosen one, Jesus is Israel. All that Israel was as a patriarchal clan under Abraham Isaac and Jacob, as a priestly collection of tribes under Moses and as a kingdom under David and Solomon served as shadows to Christ's substance. What this means is that the church does not replace Israel. Rather, the church is Israel in Christ.
Israel, throughout the old covenant, merely served as a foretaste of the glories of Christ. The covenant people of God in the New Covenant taste these glories in their fullness through union with Christ in the church. Under the Old Covenant Israel offered sacrifices on an altar. In the New Covenant we have come to find that Jesus is the sacrifice and that we, as his body, are called to present our bodies as living sacrifices (Rom. 12:1).
When we begin to understand the particularities that the New Testament authors employ we begin to see the mission of the Church, Christ's body, filled out in the pages of the Old Testament and in the life of Christ. This is why Paul writes elsewhere that he is "filling up what is lacking in Christ's afflictions." (Col. 1:24) Paul is not implying that Christ's suffering was not enough. Rather, he is assuming the mantle of Christ, as a member of Christ's body, to serve the nations as a priest and to present his own body as a living sacrifice as Christ, the head of the body had done.
Food for thought.