Peter puts the text for his reasoning at the end, rather than at the beginning. It’s a quotation from the prophet Isaiah 28:16.
Because we are living stones, we are not simply laid passively in the building, but we deliberately look to Christ, glancing along at him to model ourselves on him. We often consider his place in the building and all that he did in his life to secure that place, for he has earned his position by his perfect obedience to the Father. We consider his strength to bear up the whole building for it is as if the whole building rests on him (elsewhere he is called the foundation of the entire church). We think of his perfect alignment with the plumb line of God’s righteous law; he alone has fulfilled the law and is therefore qualified to redeem God’s people. In a way that is not true of any building made with dead stones, each member of the church is directly in contact with him by his Spirit, and not separated from him by other believers who are closer to him than they are.
What is the building? It is the greatest building in the history of the world. It is the church of the living God. It has its people, its members, its converts out of every generation and every land under heaven. It is the greatest building. This corner stone – Christ and his suffering and death on Calvary – supports the most enduring building. Of course, it has endured across the centuries, the church of Christ to the present day but this is a building that lasts for all eternity. It is the most attacked building but it will withstand every attack. It is the most beautiful building. When we think of ourselves, we think, how can this be a beautiful building? Here am I with all my foolishness and all my sins, and yet looking around at so many Christians, we see what the Lord has done in their lives, what people have become, and how patient and how unselfish the Lord has made their characters. It is the most productive building, sending out the message of the gospel into all the world. It is the happiest building, because no matter what sorrows it goes through, his people know that they have been saved by Christ and have a foothold in heaven.
The translation ‘confounded’ is very good. You pray earnestly for something and you see a need. Will you be let down? Will you be put to shame? Will anybody be able to point the finger and say, ‘You trusted in that God of yours, and he’s let you down. It hasn't happened and it doesn't work out’? Never. You will never have any cause to be distressed, perplexed, confused, disappointed. Not in life, and certainly not in death, when the light of this world goes out, and you breathe your last. You will be ushered into the presence of God and of Christ. There will be such a time of acclamation and wonder and praise, that you will never be disappointed.