What does Luke 18:33 mean?

Once again, Jesus is prophesying about His crucifixion and death (Luke 9:21–22, 44–45; 13:33). His training session with the disciples is quickly coming to an end. They are deliberately making their way to Jerusalem (Luke 18:31).

Jesus has already told the disciples He will die, but he uses particularly graphic language here. He tells them He will be "delivered over to the Gentiles and will be mocked and shamefully treated and spit upon" (Luke 18:32). The Jews will blaspheme Him, beating Him in a way that mocks His deity (Matthew 26:67–68; Luke 22:63–65). The Gentiles will mock His majesty, clothing Him like a king as they beat Him and spit on Him (Mark 15:16–19).

Then, the Roman soldiers will flog Him. As the soldiers put the crown of thorns on His head, His back will pour blood and His flesh will hang in strips. As they put a purple robe on Him, His blood will trickle to the ground (John 19:1–2). The blasphemy they will commit against His deity will be accompanied by violence to His body. Then, they will kill Him by hanging Him on a cross.

And yet, there is one more thing: He will rise again on the third day. After just enough time to satisfy Jewish tradition that He is truly dead, He will come back to life and leave the grave.

The disciples have heard this before, but they're still confused. How could the Messiah die? It is because He is the Messiah that He must die and be raised again.