The belief in an expected reformer and a saviour of humanity is not peculiar to the Shi'ah School of Islam. It is common not only to all the Muslim sects, but is also shared by all the great religions such as Christianity, Judaism, Buddhism and Zoroastrianism.
In this quest for the truth about the Mahdi there is no distinction of any caste, creed, or country. The quest is universal, exactly in the same way as the Mahdi himself is universal. He stands resplendent high above the narrow walls in which humanity is cut up and divided. He belongs to everybody. For all that and much more, what exactly is the Mahdi? Surely that is the big question which the thinking people all over the world would like to ask.
It is only Islam that has given this concrete shape to an abstract idea. The Mahdi is not to be born in the distant future. He is already living amongst us and shares our joys and sorrows: His appearance will mean not only the materialization of an Islamic aspiration, but will also be the realization of a hope cherished by the entire humanity.
Prof. Henry Corbin of Sorbonne University, says:
"To my mind the Shi'ite is the only sect which has preserved and perpetuated the link of Divine guidance between man and God through its belief in the Imamate. According to the Jews the Prophethood, a real link between man and God, came to an end with Moses. They do not believe in the Prophethood of Jesus and Muhammad. The Christians too, do not go beyond Jesus. The Sunnite sect has also stopped at the Prophet Muhammad and believes that the link between man and God has been severed with the end of the Prophethood".
p: 2