Announcing the future can be dangerous.  At work, employees are often the last to know!  It is a way to control and protect change-processes, so that the corporate objectives are not sabotaged.  But it is also important to manage expectations lest the staff wrongly assume what may happen in the future.  After the transfiguration, the disciples' hopes about Jesus would have dramatically increased.  They had seen His power and glory (Mark 9:1).  Surely, this was the time for Him to reign as King; and them to reign with Him (Mark 10:35-37).

But there were to be two future events: suffering and death, and then glory.  Jesus was preparing them for both, even though they would be spaced thousands of years apart.  It was essential for them to have confidence in the long-term outcome; but before then, Jesus had to die.  They had to be prepared for the trouble ahead.  None of it would be out of God's control, it was all part of the plan.  Likewise, 'rising from the dead' did not make any sense to them.  Jesus taught them what the Holy Spirit would later explain (John 16:12-15).  

The expectation of 'Elijah' coming was derived from Malachi 3:1-4 and Malachi 4:5-7.  God said that before the Messiah (Christ) was revealed, Elijah would come.  The amazing sight of Elijah transfigured with Jesus, clearly identified Jesus as the Christ (Mark 9:4).  But Jesus had also been clear that John the Baptist had been the 'messenger of repentance' (Elijah) for the people (Matthew 11:13-14).  Also, Jesus pointed to Isaiah 53:3 identifying that He was the long-prophesied suffering servant of God.  Then Jesus reminded them that John the Baptist was killed because his message demanded too much personal change - which Herod's wife, for one, was not willing to contemplate.

We find it difficult to process multiple bits of information, especially when some appear contradictory.  But the Lord knows the future and will lead us through the pain to His glory.  As Jesus prepared the disciples for the unique circumstances that would surround Jesus and themselves, so the Bible is designed to prepare us for life and eternity ahead.  There are two sets of future events: our earthly circumstances and the eternal glory ahead.  We must not confuse them, otherwise we will be despondent in our present pain and ignore God's message of hope for the future.  It was not easy for John the Baptist: he wondered if he was suffering in vain (Matthew 11:2-6).  He gave out God's message - some listened and another cut his head off.  As Jesus indicated, people usually get their own way ... and removing a truth teller to avoid the message is not just modern business practice!   But those who hear, believe and respond get two things: the ultimate blessing of the Lord's reward, as well as the privilege of being next in the firing line!   So, do not be surprised at the troubles ahead (1 Peter 4:12), nor lose sight of the glory to come.