The parallels with the Old Testament church didn’t end with just salvation and our being called out and chosen by God. The question is, Called out and chosen for what? Peter quickly gives the answer.
Peter points out that this special relationship is for a purpose. Christians are to “proclaim the excellencies of him who called you out of darkness into his marvelous light” (1 Pet. 2:9, ESV). This is what ancient Israel was to do. God called them to be witnesses of Him to the world. God’s purpose was to bless the whole world through ancient Israel, His covenant people.
Ancient Israel, as the covenant people, had a mission to reach the world with the gospel, the salvation offered by the Lord. Christians have the same divine mission. They are called to share with others their experience and knowledge of God and what He has done for the world through Christ.
Read 1 Peter 2:10. Why is this text so central to the whole mission and purpose of Christians?
The world is steeped in sin, in death, in impending doom. But Jesus gave His life to save everyone from this destruction. As with Israel of old, the terms of honor are also terms of responsibility. Christians have an extraordinarily high status: that of the people of God. But this brings the responsibility to invite others to share in that high status. As 1 Peter 2:10 states, Christians now form their own people. They once were not a people, but have now received mercy to become a holy people (see Hosea Chapters 1 & 2). In the Bible, “holy” usually has the meaning of set aside for the purpose of worship. Therefore, as a “holy” nation, Christians are to be separated from the world, a distinction seen in the kind of lives that they live. They are also to be like a fire on a cold night, which will draw others to its warmth. Christians are tasked with the responsibility of sharing with others the glorious salvation of which they have partaken.