After speaking of young or immature Christians' need to grow through the Word of God, Peter explains that the Body of Christ is a holy nation, among other things, terms that were applied to Israel in the Old Testament.
1 Peter 2:1-10
New King James Version (NKJV)
2 Therefore, laying aside all malice, all deceit, hypocrisy, envy, and all evil speaking, 2 as newborn babes, desire the pure milk of the word, that you may grow thereby,[a] 3 if indeed you have tasted that the Lord is gracious.
The Chosen Stone and His Chosen People
“Behold, I lay in ZionA chief cornerstone, elect, precious,And he who believes on Him will by no means be put to shame.”[b]
7 Therefore, to you who believe, He is precious; but to those who are disobedient,[c]
“The stone which the builders rejectedHas become the chief cornerstone,”[d]
“A stone of stumblingAnd a rock of offense.”[e]
They stumble, being disobedient to the word, to which they also were appointed.