An architectural term denoting the top stone in a building or wall. If it caps an arch it is called a keystone. The expression is used twice in the Old Testament ( Psalm 118:22 ; Zech 4:7 ). In Zechariah 4:7 it is clearly the capstone of the temple that is in view. The meaning in Psalm 118:22 is less clear ("keystone" JB; "capstone" NIV; "cornerstone" NRSV). The Hebrew is translated by the Septuagint as kephalen gonias, literally, "the head of the corner." This term has made its way into the New Testament five times ( Matt 21:42 ; Mark 12:10 ; Luke 20:17 ; Acts 4:11 ; 1 Peter 2:7 ). Psalm 118:22 evidently refers to the king who was disallowed, but then acknowledged to be the rightful ruler. Jesus makes use of this psalm in a parable referring to Israel and its rejection of him as Messiah ( Matt 21:33-44, ; and parallels). In Acts 4:11 Peter makes use of Psalm 118:22 to defend himself against his Jewish detractors.
In all these passages it must be acknowledged that "capstone" or "cornerstone" would make an equally good translation. It is 1pe 2:7 that tips the scales toward "cornerstone." These three passages ( Psalm 118:22 ; Isa 8:14 ; 28:16 ) are used together to make the point that Christ is supreme, and two of these passages ( Isa 28:16 ; 8:14 ) clearly refer to a cornerstone.
So the Zechariah 4:7 passage is clearly "capstone" but the remainder are probably best taken as "cornerstone, " with the point being that Jesus was rejected by the ones who ought to have known him (builders = Jewish leadership), but God has exalted him to be the chief stone above all, the very head of the corner, on which all else depends.
Walter A. Elwell
See also Cornerstone
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