That is how it is with the promises God made to Abraham and his descendant. The promises were not made to many descendants, but only to one, and that one is Christ.
They are no longer part of Christ, who is the head of the whole body. Christ gives the body its strength, and he uses its joints and muscles to hold it together, as it grows by the power of God.
Each one of you is part of the body of Christ, and you were chosen to live together in peace. So let the peace that comes from Christ control your thoughts. And be grateful.