The Occultation ( غيبة ghayba) in Shia Islam refers to a belief that the messianic figure, or Mahdi, who in Shi'i thought is an infallible male descendant of Prophet Muhammad, was born but disappeared, and will one day return and fill the world with justice and peace.
It means that people should not publicly claim to be in contact with Imam Mahdi (A) and use that as a grounds for their authority over people. It should also not be used as a justification for telling people what to do (for instance, telling people to change the shari'ah, or to give them money, or to follow a certain military leader, or to do anything else, because they say that this is what Imam Mahdi told them).
It is possible to meet Imam Mahdi (A) during the occultation and gain guidance or assistance, but this is a private matter, and it is between the individual and Allah whether or not that person truly met Imam Mahdi (A) or not.
The fact of the Twelve Imams after the Prophet of Islam is an order from Allah (SWT). No one has right to say or suggest on any matter which has been decreed by Allah (SWT). Allah Knows every thing including all the future, so, there is no point in putting such questions from us. Allah Knows everything and He is The Absolute Wise, All Knowung, Most Merciful.
We have many narrations that Sahm Imam which is half of the Khums must be given the Marje' of Taqleed being a deputy of the Imam during the occultation of imam Al-Mahdi (AS). You can read many of theses narrations in Wasa'il al-Shia by Al-Hurr Al-A'amily in the chapter of Khums.
The existence of the Infallible Imam is necessary, but it is not necessary for every one to meet him, especially when certain circumstances of danger require him to be away from eyes of the enemies.
Prophets like Prophet Musa (AS) and Prophet Muhammad (SAWA) and Imams like Imam Musa Al-Kadhim (AS) other Imams during jail periods, were in occultation during times of crisis.That did not mean that they were not existing during such periods of occultation. They always had their own ways to guide people even during being away from the public life.
Imam Al-Mahdi (AS) is also in touch with the Ummah through sincere believers who are entitled to meet him and receive his guidance. Imam Al-Mahdi (AS) is in occultation but he is never absent. His guidance to the Ummah is the guarantee of saving Muslim Ummah from going astray.
Part of the responsibility of a leader is to know what is happening to his people. This is especially true for a divine leader (prophet, Imam).
Not all human beings have the qualities necessary to be good leaders. Some people have the social, intellectual, and emotional capacity, foresight, initiative, wisdom, and planning and communication skills to be great leaders. Most people do not. But that is ok, because we only need a handful of great leaders.
So, bearing this burden might be very difficult for the average person. However, the Imam is not an average person. Allah would not give the Imam this responsibility if he did not have the ability to bear it, as Allah says in the Qur'an that He does not burden with something beyond their capability. Because the Imam is at the highest level of spiritual perfection (as well as intellectual and emotional perfection), he has the capacity to handle many things that regular people cannot. Also, when people are truly at a high level of faith and have a deep and sincere connection with God, this enables them to bear things that other people cannot.
Still, of course, we should try our best to give the Imam a good report about our deeds and circumstances, and try to work as hard as we can to improve things around us!
1. Imam Al-Mahdi ( AS) during his major occultation meets , teaches, and helps people , but people do not recognize him during the meeting but very few of the very pious believers who have a high degree in faith and know him.
2. Pious believers never claim nor disclose meeting Imam Al-Mahdi (AS). Pious believers know that Imam Al-Mahdi (AS) must be away from the enemies, so they do not disclose any information about him.
3. Those who claim in public that they met Imam Al-Mahdi (AS) or brought a message from him, can never be trusted.
4. Hundreds of very pious Ulama and believers have met Imam Al-Mahdi (AS) in hundreds of occasions. Many books were compiled in this subject by great scholars like Al-Muhaddith al-Noori in his book Dar Assalam and others.
5. We pray in Du'a al-'Ahd دعاء العهد to be granted seeing the face of our Imam Al-Mahdi (AS): اللهم أرني الطلعة الرشيدة والغُرّة الحميدة واكحل ناظري بنظرة مني إليه.
This means that seeing him during the major occultation is possible for certain very pious persons.
Thanks for your question.
There are many interesting and well-written books about Imam Mahdi (aj).
I recommend the following ones:
Al-Imam al-Mahdi, The Just Leader of Humanity
An Inquiry Concerning Al-Mahdi
The Promised Savior: An inquiry into the imamate of Imam Mahdi (as) from the viewpoint of Muslim thinkers
The Occultation of the Twelfth Imam (A Historical Background)
That is just one small portion of texts concerning Imam Mahdi (aj) that can be found at Al-Islam.org, there is a whole section dedicated to him (aj):
Hope this is helpful inshaAllah.
Every community needs a perfect leadership to guide them to the right and avoid them from the wrong.
Allah The Glorious Has ordered people to follow the prophets then their successors. The last successor of the Prophet Muhammad (SAWA) is Imam Al-Mahdi (AS) who is at present under occultation by order of Allah (SWT) because of certain circumstances. Imam Al-Mahdi (AS) himself ordered the followers of Ahlul Bayt (AS) to follow during his occultation the most learned pious Ulama. (Wasaa'il al-Shia, Volume 27, Page 131.
Some persons misunderstand the meaning of Taqleed and ask about its validity . We invite them to think :
1. Is it possible for any Muslim to claim that Allah, The Most Glorious wants to leave the Ummah with out guide during the occultation of the Infallible Imam ?
2. Who is the best to guide the Ummah better than the most learned about the teachings of Ahlul Bayt (AS) with piousness?
3. Who can guide the Ummah to Islamic rules on new issues during the occultation better that the most learned and pious, who are the Maraaje' of Taqleed?
No community can remain protected from deviation if they do not follow a pious leadership and there is no leadership in the whole world more pious than our Maraaje' of Taqleed who have the maximum knowledge about Islam and highest level of piousness.
No. This claim is untrue.
All our scholars accepted every message from Imam Al-Mahdi ( AS) which came through authentic source like the four emissaries.