And what makes you think the Mahdi is going to be widely accepted initially? I think you have not read enough my brother, nor have you studied his subject enough. Firstly, we know that Islam will begin as something strange at the time of the Mahdi, contrary to what scholars state today. Today, we see scholars and ordinary Muslims be prideful due to increasing Muslim demographics, yet the Prophet(SAW) says something else, he says Muslims will be great in number but quantity does them no good. And he states that Islam will be strange, even though most Muslims today think that Islam is at its best stage or best form.
And we study further, we know the Mahdi will experience similar consequences of the Prophet(SAW) too, meaning he will be rejected by most people. Some Muslims think only the governments will oppose him, and some Muslims go even farther and claim he will have allegiance to a country and advance such country's agenda, that is not the case, he will not have allegiance to nobody, and even ordinary Muslims will reject him.
People don't study God enough .... If you look at history, God catches everyone by surprise. The non-Arab Jews and Christians expected the coming Prophet to be non-Arab, and God sent them an Arab Prophet. That is one example, and with the Mahdi, Muslims expect a 40 year old handsome man, dressed in a thobe, that will bring secrets from the Quran or some kind of new knowledge, and that he will be some hyper nationalist character who peddles along other peoples agenda. I tell you once again God will catch everyone by surprise. The Mahdi will be young, average looking, and seem like a totally normal person with no secrets or special powers or special knowledge, the only secret he will carry with them, is that of his heart. He has the best heart out of anyone else on the earth, and that's why God chose him.
And he will not help anybody from among Muslims, if anyone seeks help or acceptance, be spiritual, and even non-Muslims, can be spiritual in their own way, it's good and healthy to be spiritual. If you have something you need to settle with God, settle it with him, he is your Lord after all. The Mahdi is not going to make anyone a righteous person if they don't have the heart to be one. And he will not have time for people, he will not be making sermons and lecturing people. He will be 'fixed' by God in one night, what this means in my opinion, is he will be addressed with task from God, a very simple task with no explanation how to achieve. And this will make him very fearful of God, to point where he is less stressed about how to achieve the task, and more stressed by fact that now he knows is very close to God, and God is watching his every move, and he will die and meet God after he achieves this task(he will not live long), and that fear overrides everything, and that's how God 'fixes' him, and he will be paranoid and able to achieve results quickly.
We don't need to go further into the details of this person, because he is misused by many Muslims. Let God arrange things, in mean time, that should not stop Muslims from seeking justice in the Muslim world, from the scholars, governments and other peoples. It should not make them hopeless and not ambitious, on contrary, Muslims should keep striving to be the best, and strive to have the best character. What's most important right now is ending the strife and working on character of Muslim people, and strive to be ambitious in Muslim societies. Don't allow governments and their clerics to distract you, tell you the Mahdi will fix everything, but until then, don't speak against us or suggest reform , or ... or .. or , etc..... No, that's not how it works, Muslims should urge reform more right now than at time at of Mahdi, because that is the purpose, that without a clear sign, there is faith to strive for what is good, and that is the purpose of life.
That's all I want to say for now ....