Since the belief in the promised Mahdi has been Islam’s alter ego and has the most obvious manifestation in the Holy Prophet’s Announcements, all Islamic sects have unanimously accepted it.It is evident that the abuse of this issue by some of the pretenders who have resorted to these religious teachings to seek power and legitimacy should not be regarded as a proof of incompetency of Mahdiship (Messianic, Parousia). Unfortunately, most of orientalists are not able to differentiate between the reality of Mahdiship and its abuse and have mingles these two in their historical researches. Certainly, this issue is normal to some extent; because, there have been some people who have talked about Mahdiship but used it to achieve their own goals; in a way that orientalists have come to this mentality that this discussion is more an intrigue and excuse in the hand of political protesters and opponents than a reality. The present paper has attempted to resolve the ambiguities and correct their attitudes toward Mahdiship by investigating and criticizing the remarks of some of western ISLAMICISTS, which have been included in reputable and reliable encyclopedias.