This song is really sad when you think about it. It's about a man who has reached middle age and has lost his ideals. You have to follow the whole sequence "I'll put away childish things/I've put away childish things." "Heaven" represents these ideals--the good things in life. But he still believes in ghosts. "Ghosts" can mean whatever traumatizes him, whatever skeletons are in his closet.
This song is really sad when you think about it. It's about a man who has reached middle age and has lost his ideals. You have to follow the whole sequence "I'll put away childish things/I've put away childish things." "Heaven" represents these ideals--the good things in life. But he still believes in ghosts. "Ghosts" can mean whatever traumatizes him, whatever skeletons are in his closet.