When the builders in Jesus’ day were using stone to construct a building, they would start with the cornerstone, which provided a strong base for the corner of the building. It was important to use the right stone. If the builders found a stone that was the wrong size or shape, they wouldn’t use it. It would be rejected because it wasn’t fit to use.
That’s how the religious leaders were going to treat Jesus, and He knew it. But Jesus quoted a well-known line from the book of Psalms (verse 17): “The stone the builders rejected has become the cornerstone” (Psalm 118:22). Although He would be rejected by the religious leaders, He would turn out to be the foundation and focus of God’s Kingdom, and then they would be judged for rejecting God’s Messiah.
Ironically, the religious leaders immediately tried to arrest Jesus, because they knew what He meant! Jesus had compared them with the religious leaders from Israel’s history, who had often killed God’s prophets. Now the Father had sent His own Son, and this group of leaders were going to have Him killed as well (verses 9-15). They felt threatened by the truth, and the way Jesus exposed their fake goodness. The were scared of losing their power and influence over the people. But no matter how hard they tried, they couldn’t catch Him out with their spies and their sneaky questions (verse 20). They were going to have to stoop even lower to rid themselves of Jesus.
“The stone the builders rejected has become the cornerstone”
Luke 20:17