Job realizes his hope that he would be called from the grave, away from his sin, does not have a observable precedent. This has not happened by Job's lifetime so he begins to despair, looking at how everything in creation wastes away. But the true hope a Christian has in Jesus. In Jesus we see a resurrection where our sins are removed from us and we are brought into a new creation where there is no decay. We are new creations now, living in the forgiveness of Jesus unto eternity.