According to Nietzsche, Christians are vermin whose religion brought about the fall of the Roman Empire, inhibits man's abilities to pursue true value and good, and serves vampire priests who suck on society like leeches. Martin Luther killed the Renaissance, sin was invented to control the masses, and Muslims have every right to hate Christians because Christianity was responsible from keeping the wonderful Islamic culture form blooming and showering the world with intellectual gifts.
My opinions on the arguments of The Anti-Christ vary, but I'd be a liar if I saw Nietzsche didn't make it entertaining. To borrow a phrase from Duke Nukem, he basically rips off the heads and shits down the necks of those he despises.
I think it was the publisher who ultimately decided on the title of the book. He probably felt the original title was too harsh: The Comedy Central Roast of Christianity.
I'm thinking of making my final paper for Rhetoric of Religion be about the shock and awe type of rhetoric you see from characters like our boy Friedrich and modern nuts like Glenn Beck.