TEHRAN (Reuters) - His call for the destruction of Israel may have grabbed headlines abroad, but it is President Mahmoud Ahmadinejad's devotion to a mystical religious figure that is arousing greater interest inside Iran. In a keynote speech on Wednesday to senior clerics, Ahmadinejad spoke of his strong belief in the second coming of Shi'ite Muslims' "hidden" 12th Imam. According to Shi'ite Muslim teaching, Abul-Qassem Mohammad, the 12th leader whom Shi'ites consider descended from the Prophet Mohammed, disappeared in 941 but will return at the end of time to lead an era of Islamic justice. "Our revolution's main mission is...