If this guy says it is impossible for ghosts to exist I should invite him to my house and let him watch the little girl walk down the hallway, or let him sit in my room at night and listen to the random whispers. Better yet I will take him to a family friends house where you can actually sit in the living room and count them as they go by.
Zombies? Yes if you qualify what happens to people when introuced to a certain amount of puffer fish poison then yes they are real. Well as real as we are going to get until the invasion comes :D.