Cornerstone See also Jesus Christ The main stone forming the corner of the foundation of a building. Jesus Christ is called the chief cornerstone (Eph. 2:20). The stone that the builders refused has become the head stone of the corner, Ps. 118:22 (Matt. 21:42–44; Mark 12:10; Luke 20:17; Acts 4:10–12). The Jews rejected the cornerstone, Jacob 4:15–17.