31 Then He took the twelve aside and said to them, “Behold, we are going up to Jerusalem, and all things that are written by the prophets concerning the Son of Man will be [a]accomplished. 32 For He will be delivered to the Gentiles and will be mocked and insulted and spit upon. 33 They will scourge Him and kill Him. And the third day He will rise again.”
34 But they understood none of these things; this saying was hidden from them, and they did not know the things which were spoken.
Luke 18:31-34
Jesus a third time predicts His death and resurrection. This third time in Luke, Jesus shares with His apostles what comes next for Him, that the prophecies will be fulfilled in Jerusalem. He will be delivered to the gentiles, mocked, insulted, spat upon, scourged, and killed… that He shall rise again on the third day.
It is specifically pointed out each time that the apostles do not understand what He is telling them. They were Jews, they knew the scriptures and prophecy, they were living it! Still the thought that not only would Jesus be tortured and killed, but rise again on the third day was incomprehensible to them.
How could the Son of God who they have known, loved, and followed for three years, Who performed miracles and wonders before them, suffer and die? I only have conjecture here based on what I have read, but I can understand it simply not making sense to them. Such a loss, such a gain was beyond them.