Leave aside the aspect of Mahdaviyat...
Leave aside the aspect of Mahdaviyat, they have not even spared the belief in Revelation, Prophethood and above all : Monotheism.........................The only reason being that after accepting the materialistic ideas, it is impossible to believe in transcendental ideas. Since the belief in Mahdaviyat is also a belief in hidden concept and more over to believe that Hazrat Mahdi (a.s.) is a mortal like us and though he passes his life amongst us, he is far from our vision.
Hence this belief for materialists is like adding insult to injury. Thus to relieve themselves from this belief they reject this idea outrightly and refuse to accept the existence of Hazrat Mahdi (a.s.). Subsequently, the refusal of first group increases the haughtiness of the second group. There are innumerable replies to the doubts and baseless notions of both the aforementioned groups. And these doubts themselves are self-contradictory and inherently weak.
But it is not possible for us to quote those replies over here. Interested readers may refer to the books compiled redundantly to refute the ideas of skeptics and disbeliever, only through those parameters which are accepted by consensus of Muslims Viz. 'Quran and Traditions.........And in this regard, we will also furnish proofs from some very reliable and trustworthy Ouranic exponents.............and traditionalists......... of 'Ahle-Sunnat from their very authentic books.
And for the understanding of a layman we will also produce some historical evidences from history and view points of ancient Sunni scholars. So that the truth becomes manifest and explicit and righteous may be notified from them. I) The Interpreters of Quran : have mentioned countless ayats regarding Hazrat Mahdi (A.S.) from Quran. And moreover many books have been complied by the name of "MAHDI IN QURAN".
But over here we will confine our discussion to those ayats which, interpreters have related it to Hazrat Mahdi (A.S.) by some source or reference. Imam Abu Ishaq Thalabi who is a renown exponent of Quran writes in his exegeses in "The ayat of Quran.........Means. indicates means the war between Quraish and Almawali in which Quraish will emerge victorious.........relates to......which means the Rulers of Bai Abbas and ....... is letter to Hazrat Mahdi which means!
.......chapter...7 related from Naeem Ibne Hammad) Imam Abu Ishaq Thalabi writes in the ...