There are two levels in this saying. The first level is to see that this is Jesus' word to us about death. Jesus Christ, as the doorway to life after death, offers resurrection to us all. His resurrection of Lazarus proves the power of his words, and his own resurrection will become the final sign of our resurrection on the other side of this life. Some will say there is nothing more than this world.
Death is the end.
Some will say that death is just sleep and we will all wake up in a new life. Some say death only leads to reincarnation in another life. Some rely on the Greek idea of the immortality of the soul. None of those are good enough for me. In this modern world I am surprised how little we talk about this gift of life after death.