All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
We have already issued Fatwa 81406 clarifying the reality of this sect that it is a heretic and misguided sect, so please refer to it. As regards the Hadeeth about the Mahdi which you mentioned in the question, it is a Dha’eef (weak) Hadeeth, and it is classified as such by Ath-Thahabi and Ibn Hajar and others.
Nonetheless, Ahlus-Sunnah Wal Jamaa’ah believe that among the signs of the Hour is the coming of the Mahdi at the end of times, and there is much authentic evidence which we already mentioned in Fatwa 82108.
As regards the claims of the followers of this sect that their Mahdi sees Allaah and that he speaks with Him directly, then this a lie and misguidance as it is not possible for anyone to see Allaah in this life as it is confirmed that the Prophet said: “…And know that you will not see your Lord until you die.” [Ahmad]
Also, their Mahdi claiming that Allaah revealed to him additional religious obligations is a pure lie and clear charlatanism as there is no revelation after the Prophet Muhammad . Indeed, Allaah completed the religion during the life of the Prophet and He completed His Favors upon us; Allaah Says (what means): {This day I have perfected for you your religion and completed My favor upon you and have approved for you Islam as religion.}[Quran 5:3]
Concerning their claim that it is an obligation to pledge allegiance to the members of the family of their Mahdi, then we do not know what they mean by that. In any case, the real Muslims amongst them have their rights as Muslims according to the Sharee’ah like other Muslims.
In any case, it is an obligation for whoever has religious knowledge to clarify the truth to those people and endeavor to bring them to the truth and warn the Muslims against them as a way of providing advice to the Muslim nation. Besides, a person who is not well-grounded in religious knowledge should avoid debating with the people of falsehood so that they would not make him confused about his religion.
Allaah Knows best.