In my opinion, death is death. You die, and you cease to exist. But the thing is, no-one will ever know, for sure, whether there is an afterlife. When you die, you are dead, and there's no chance for pondering your situation. Death will not be a Sopranos-style "cutting to black, it will just be nothingness for eternity. Therefore, people who believe in an afterlife will never know that they are wrong, they will just die. Kind of irritating, in a way...