Peter bases all of the commands in this chapter on who Christians already are. His order of logic is crucial: not “Do this, in order to be this,” but “You are this. Therefore do this. Be who you are. And you are who you are because of Christ.”
We are reborn - like newborn infants, who need the pure food of the Word (2). We are like living stones, being built into a spiritual house (5a), a holy priesthood, offering sacrifices to God (5b). We are both God’s temple and the priests who serve in the temple. We are, in short, God’s new Israel.
Thus we are, in a string of Old Testament references:
. . . a chosen race, a royal priesthood, a holy nation, a people for his own possession . . . 1 Peter 2:9a
We are God’s people, having received mercy from Him (10). And now we no longer belong to this world, but one to come - thus we are sojourners and exiles (11).
These comprise the fundamental identity of anyone who has “tasted that the Lord is good” (3). And as with any identity, there are many parts. All of them we receive and perceive by faith in Christ, who actually is all these things.
Perhaps the most important aspect of our new identity is the one that’s repeated - we are a priesthood, both “holy” (5) and “royal” (9). Meditate on these words. Then be who you are already are, by faith in Christ.