The New Testament has several ways of expressing the union that exists between Jesus and his people. Jesus, for example, used the illustrations of a vine and its branches and a shepherd and his sheep. Paul described the relationship as similar to that of a bridegroom and his bride and of a head and its body. Peter here uses the picture of a building composed of a cornerstone and stones, with Jesus being the cornerstone and his people being the other stones in the building. It is tempting to see here an allusion to the promise that Jesus made to Peter after his confession of Jesus as the Son of God concerning the certainty of his building his church.
The first detail that we can notice is that the role of Jesus as the cornerstone was prophesied long before he lived in this world. Peter cites from the prophesy of Isaiah (28:16) and says that the prophet’s words concerned the future place that the Messiah would have in the outworking of God’s kingdom.
A second detail that Peter mentions is the purpose of God the Father. It was he who planned the position that Jesus would have. We see this position in the sentence, ‘Behold, I am laying in Zion a stone, a cornerstone chosen and precious.’ In the sentence, we can also see the esteem or value that the Father gave to his cornerstone.
When did the Father lay his Son as a cornerstone?’ The answer to this question is found in verse 7. The laying occurred after he had been rejected by some as a suitable cornerstone. Peter here quotes another Old Testament reference, Psalm 118:22, which he had also quoted in his sermon preached years before in Jerusalem when he informed the Jewish leaders that they had rejected God’s Messiah (Acts 4:11). He had heard his Master refer to the same verse when he rebuked the chief priests and Pharisees (Matt. 21:42).
They had assessed Jesus and rejected his teachings about his kingdom. Their conclusion was that he was not fit to be the cornerstone; instead they deduced that he was a fraud and, keeping the illustration of stones, they proceeded to throw him into the place of rejected material. In a marvellous way the time of his rejection by men was the time of his positioning by the Father as the cornerstone.
Paul uses the same idea in Ephesians 2:20 when he says that Jesus is the cornerstone. There, Paul’s main focus is the unity between Jews and Gentiles in the church that Jesus brings about as the cornerstone. A cornerstone would bring two sides of a building together, and we can see how Paul could use it to describe how Jesus brought together Jews and Gentiles. In ancient buildings, it was the cornerstone that held the building together. Similarly, the only one that can hold the church together is Jesus, and we should not give the impression that someone else can do it.