Nihilism is not lack of belief in anything. I'm sure Nietzsche believed in commonly accepted facts that most people believe in anyway. Nihilism is thinking that the universe has no purpose, which is a perfectly reasonable philosophy, one that I share with Nietzsche.
brief description paraying it isn't a juke: he means a lost of valor due to the past(apollineus)valors destroyed. nihilism can be passive or active, the last one will be useful for arrive to the ubermensh staus. i skip lot of passage, so if you want some more, just check on a book.