1 Peter 2:4 As you come to him, the living Stone - rejected by humans but chosen by God and precious to him -
God chose Christ to be the living stone, the chosen cornerstone, to be there in the foundation of the earth for our sakes.
We are to be like living stones as well, built around the chosen cornerstone.
This has all been put in place for us because He chose us, and we are very special to Him.
We are, to Him, a royal priesthood built around the head priest Christ.