For many, the war with Iran — and the killing of Ayatollah Ali Khamenei — might seem like the climactic end to a long, brutal reign of terror by the theological clerics who have run the country since 1979. But a Fox News Digital investigation reveals that, for certain hardline Shiite ideologues, including in the U.S., this is not an ending but a prophetic showdown that will usher in the arrival of the "Mahdi," a messiah, according to Islamic eschatology, or the theology of end times. In this prophecy, Mahdi will emerge to battle Dajjal, the Islamic equivalent of the...