Jesus told His disciples (and you and me) that He will return in such a way that all people, everywhere, will see Him – as lightning flashes across the sky.
  Then Jesus went on to say:
(NASB) Luke 17:25 “But first He (Jesus) must suffer many things and be rejected by this generation.”

  Suffering and rejection of the Son of Man is the keystone for your salvation and mine.  Without Christ Jesus’ suffering and rejection, His death and resurrection…no one would know Him as Savior.
  That generation living at that time in the days of Jesus would reject Him as their Messiah…and that would be one of His points of suffering.

  That generation ignored or refused to understand that their Scriptures (the Old Testament) foretold of Messiah:
  Who His mother would be ~ Isaiah 7:14 – a virgin (Luke 1:31)
  Where He would be born ~ Micah 5:2 – in Bethlehem (Luke 2:4)
  What would be some of the circumstances surrounding His birth ~ Hosea 11:1 – God called His Son out of Egypt (Matthew 2:13-15)
  What His ministry would be like ~ Isaiah 9:1-2 – He preached to Jews & Gentiles
  What His suffering would be ~ this is explicitly said in Psalm 22, Isaiah 53
  What would happen to His dead body ~ Isaiah 53:9 – assigned a grave…with the rich (Matthew 27:57-60)
  What we know about His resurrection ~ Psalm 16:10 – not abandoned to the grave (Acts 1:1-3)

  And many more prophecies throughout the Old Testament of Messiah’s first Advent…the first time He came as the Suffering Servant for you and me.  
  The Jewish people rejected the first Advent of Messiah because they were looking for Him to come as King.  
  And He is going to come as King over all kings, potentates, presidents, etc.

  What do you and I need to do differently from “that generation”?
  Who are we rejecting that we need to embrace, believe and place our faith in?
  It is God’s strength for these days.
  It is God’s truth in these days.
  It is God’s words of truth that warns us, encourages us and always, always, points to Him.

  By faith we are saved and that not of ourselves but through faith in Jesus Christ alone. 
(NIV) Hebrews 11:1 “NOW FAITH is being sure of what we hope for and certain of what we do not see.”