What does Luke 20:45 mean?

It is the week before Passover and Jesus' crucifixion. Jesus goes daily to the Temple Mount to teach His disciples and anyone else who cares to listen (Luke 19:47; 21:37–38). Religious leaders listen, too, trying to trick Jesus into breaking either the Mosaic or Roman laws (Luke 19:47–48). No matter what they throw at Jesus, He easily rebuffs their attempts (Luke 20:1–38).

The confrontations have been so one-sided that the Pharisees, Sadducees, scribes, and priests cease their attacks (Luke 20:26, 39–40). That doesn't mean Jesus is done. First, He shows how king David admitted he was subject to the Christ (Luke 20:41–44). The religious leaders know Jesus is applying the concept of the Christ—the Messiah—to Himself. Now, He goes on the offense. Narrowly, Jesus is speaking to His greater group of disciples, but Jews from all over the Roman Empire and Persia are listening. His message is simple: don't trust the scribes.

"Scribes" are the religious equivalent to lawyers: experts in the written Scriptures and discussions of Judaism. They can be Pharisees or Sadducees. Scribes of the Pharisees know all the Jewish Scriptures as well as the extra-biblical Oral Law which their predecessors developed to refine those concepts. Sadducees concentrate on the Torah: Genesis, Exodus, Leviticus, Numbers, and Deuteronomy. Unlike the Pharisees, they don't bother with the Oral Law.

The scribes have been at the forefront of the attacks against Jesus. When the scribes and chief priests felt too afraid of the people, they sent spies to try to trap Jesus (Luke 20:1, 19–20). They presented religious, civil, and legal riddles, and Jesus answered them all. Now, it's His turn, and He's not so subtle. His criticism here is not of religious experts of all types, but of the self-aggrandizing scribes of Jerusalem. In Matthew 23, both scribes and Pharisees are indicted.