The term "identity politics" is typically used less as a designation than as a sneer: disapproving shorthand for Balkanized multiculturalism. Arun Kundnani's new book The Muslims Are Coming! sees the subject through a different lens. For Kundnani, as Noah Berlatsky's review explains, identity politics isn't something the left does to get goodies from the government. It's something the government does to justify and expand the power of the national security state.