Jesus came from Heaven, from above, and His disciples chose to follow him, knowing that they would suffer, but that they would have an eternal reward in Heaven, thus they wouldn't be of this world either.
====Another Thought====
Scripture says that those who are born again are a "new creation in Christ Jesus." Scripture also says that believers in Christ are citizens of heaven.
Jesus is making a fundamental statement that there are two classes of men and women, those who are of this world and those who are not. Much, much more is wrapped up in this concept and would take more room than is offered here. Suffice it to say that Christ declares Himself and His followers "not of this world." To get a better feel for this divide, read the book of John, chapter 17. In fact, read John 15:18 through John 17:26.
It means that Jesus wanted his disciples to work together and be a group of people who can be united in fellowship and in life
Peter
No the disciples did not understand him when he said you will see me for a short time only.
Jesus broke some bread and said to the disciples this is my body and then he got some wine and said drink this, this is my blood.
Jesus said this when he appeared to the disciples after the Resurrection. Jews and Muslims say it frequently - as 'Shalom'or 'Salaam'.
It was Jesus himself that said this. He told the disciples that no man nor the angels nor even He did not know but only the Father in heaven knows the exact hour when Jesus will return.
the disciples followed Jesus and did what Jesus said. Jesus picked his disciples. The disciples were ordinary people. Jesus doesn't only like the people who are rich and successfully. he loves us all equally, no matter who we are or what we look like, he made us all and saw that we were good
Jesus never said. It would not be in His nature to nurture envy or create competition among His disciples.
The Acts of the Apostles describes what they did after Jesus ascended to heaven. They were then Apostles as witnesses to all that Jesus said and did, especially the resurrection. At this time disciples was also used as the name for all the Christian believers since they were all devoted followers of Jesus (no unbelieving nominalism then). Prior to Acts, the four Gospels, although centered on Jesus, record much of what the disciples (as they were then called) did and said.
Jesus was speaking to his disciples. (Matthew 16:24) Then Jesus said to his disciples. (Matthew 16:28) Truly I say to YOU that there are some of those standing here that will not taste death at all until first they see the Son of man coming in his kingdom."
Peter was the most outspoken of the 12 disciples, he boldly said that Jesus was the son of God, he is also the only man to defend Jesus in the garden.
Jesus was speaking to His disciples referring to the Roman Centurion .