Throughout the fateful years of the Cold War, the world's survival was due only to its adherence to the following rationale: Since both sides of the ideological conflict were in possession of enough nuclear weapons to destroy each other many times over, and since each had the capacity to strike back should they be attacked with their guards down, neither of them would be irrational enough to launch a nuclear strike and take responsibility for destroying the world, erasing mankind, and catapulting human culture and civilization back to the Stone Age. Despite the face that most major cities in both the East and West were targeted for destruction at some point or another, the aforementioned calculation seemed to work with humanity as a whole living under the fear of sudden and total annihilation. Strategic missiles, submarines and bombs were implemented to be in a state of constant alert in order to combat the worst, and indeed, the worst was avoided until Star Wars exhausted one party economically and opened the way for a final exit from the Cold War's state of MAD.MAD, the acronym for Mutually Assured Destruction, was aptly dubbed thus because it delineated that only mad, unpredictable leaders—of the kind that did not exist on the political horizon of that era—could invalidate that stabilizing equation and rattle world security to its core. Back then, no one predicted that any type of leadership to emerge that would defy the two main rivals of the Cold War.Yet it did.In accordance with Samuel P Huntington's theory that people's religious identities would become the primary source of conflict in the post-Cold War world, a new rival emerged on the "bloody seam line" of Islam. The Islamic Revolution in Iran of February 1979, which thrust Grand Ayatollah Ruhollah Khomeini to power and forced the pro-western and rational Shah Mohammad Reza Pahlavi to abdicate—thereby disposing one of the most formidable bastions of the US in the Middle East—generated this revolutionary change.The Mullah regime of Khomeini provided Iranian society with clerical authority, and being that he was learned and versed in theology, Khomeini was more capable than most politicians in understanding the system's intricacies, and was therefore himself referred to by the title "Imam" – a term hitherto reserved only for the twelve infallible leaders of the early Shi'a. Khomeini allegedly had the extra benefit of maintaining regular spiritual contact with the Hidden Imam, Muhammad al-Mahdi, who lived in the 10th century and is said to have never died. This last of the Twelve Imams, the Hidden Imam is also believed to be the ultimate savior of humankind who will emerge with Isa (Jesus Christ) and fulfill the prophecy of restoring peace and justice to the universe. Fast forward a couple of decades when the then-mayor of Tehran, Mahmoud Ahmadinejad widened the avenues of the capital city. Though not a cleric of any rating, Ahmadinejad was reared in the Shi'a tradition and as such is a fanatic believer in the Doctrine of the Imam. His reason for widening Tehran's roadways was to accommodate the multitudes of onlookers that would undoubtedly flock to the streets to witness the Imam's return - an event that the mayor considered to be very close at hand. After his inauguration into presidency, Ahmadinejad recounted how he had felt the aura of the Imam enveloping him when he was addressing the UN General Assembly. For Ahmadinejad, this wasn't about some messianic pipedream or a mystical vision of some kind, it was rather a very operational blueprint whose implementation must be planned and provided for. There was also the additional benefit that upon the return of the Imam, the role of Iran's Supreme Leader Seyed Ali Hoseyni Khāmene’i—with whom the president had experienced friction over issues relating to authority—would become redundant. According to Shi'ite eschatology, the end of the world is intertwined with the return of the Imam, whose arrival will be announced by violent pangs, unrest, wars, injustice and misery. Leaders like Ahmadinejad, who are imbued with messianic zeal and who are filled with hatred and bellicosity, wholly disregard any worldly circumstances or restrictions.This brings us back to our original discussion of nuclear weaponry and the resulting MAD formula that prevented nuclear annihilation during the Cold War: So long as the possibility to hasten the return of the Imam exists, someone as clinically mad as Ahmadinejad may very well decide to use his nuclear program to this end - regardless of the costs or the global consequences. After all, in the post-apocalyptic world, only the omnipotent Imam will have the power to redress the errors made by human leaders.It is high time for the US and other Western leaderships to wake up to this very imminent threat. If mad leaders like Ahmadinejad are given platforms that accord them even the smallest degree of legitimacy - at the UN, for example - and are allowed to continue in their quest to dismantle the MAD safety net that has thus far protected humanity's survival, then the only thing left on the horizon will be a global, nuclear holocaust. The writer is a professor of Islamic, Middle Eastern and Chinese history at the Hebrew University of Jerusalem and a member of the steering committee of the Ariel Center for Policy Research.