In 1924, the last caliphate--an Islamic state as envisioned by the Koran--was dismantled in Turkey. With no state in existence that matches the radical Islamic ideal since, al Qaeda, which sees itself as a government in exile, along with its hundreds of affiliate organizations, has failed to achieve its goal of reestablishing the caliphate. It is precisely this failure to create a homeland, journalist Yaakov Lappin asserts, that has necessitated the formation of an unforeseen and unprecedented entity--that is, a virtual caliphate. An Islamist state that exists on computer servers around the...