The system of the Mahdi exists in the Qur'an. The Mahdi is mentioned in story of Dhul-Qarnayn meaning there is an indication for a ruling all over the world. The Surat an-Nur, verse 55 clearly describes the way of Mahdi and propounds signs of good morality to prevail over the world. "We gave him power and authority on the earth and granted him a way to everything." (Surat al-Kahf, 84) In the story of Saul and Goliath in the Qur'an, there are signs for the Mahdi. In the time of Saul there is a prophet but Saul is sent as a Savior. - Harun Yahya