NOTES for Pe1 2:9
By calling Christians a "royal priesthood" and "a people for His own possession," the apostle thereby reminds them of the chief task of the Church, which, as we can see, consists first of all in bearing witness to the reality of the Kingdom that has already entered our world and is transforming it. Of course, the "excellence of the One who called you" refers to Christ Himself; otherwise this expression cannot be understood. But if witness to Christ is genuine, it will inevitably be first of all witness to the Kingdom that He brought into the world. Properly speaking, as Christians we could not bear witness to the world about anything else.
Of course, each of us will surely have something connected with our own tradition, cultural and religious. But witness to our tradition will no longer be our witness as Christians. It may be our witness as Orthodox, Catholics, Protestants, or representatives of one more among the many religions that grew out of Christianity. Yet such witness has no direct relation to Christ or to the Kingdom. At best it can only be our historical and cultural interpretation of Christianity.
But Jesus does not offer us any interpretations. He offers us only Himself and the Kingdom that He brought into the world. And if we truly are, according to the apostle's word, "a holy people," that is, people who have a relation to this Kingdom, then only Christ and the Kingdom can and must be the meaning of our witness. Otherwise we will very quickly cease to be what the apostle calls us to be.