Because it is contained in Scripture, "Behold, I lay in Zion a chief cornerstone, chosen, and precious: He who believes in him will not be disappointed."
There were many providences in the building of the Jewish temple, despite the fact of its being a departure, really, from the will of God; just as there were also many wonderful providences and miracles connected with the secular kingdom, which also was not really the will of God; and surely, this incident of the rejected cornerstone must be one of such wonders.  It is the perfect illustration of how the "builders," the Jewish hierarchy, rejected the true and only head of all holy religion.  Peter was fond of this illustration and told the Sadducees to their face that they were the "builders" who had rejected the chief corner stone (Acts 4:11).  In this passage, Peter extended the application to include all unbelievers as partakers of the same blame that pertained to the "builders."  Macknight's paraphrase of this verse is: