The skeptics deny the existence of Imam Mahdi (a.t.s.f.) on one pretext or the other. One of their weaker arguments relates to Imam’s (a.s.) long life. In their view it is not common for a person to have such a long life.
Doubting the prolonged life of Imam Mahdi (a.t.f.s.) belies faith in Allah’s boundless power which in fact is a sign of weak Tauheed.
Hasn’t Allah granted long life to others like, Prophet Nuh (a.s.) – a fact announced in Surah Ankaboot (29): 14? Then there are Prophet Esa (a.s.) and Luqman who have likewise been granted long life.
Not just His friends, Allah has granted long life even to his enemies, like Satan for example. Then what is so shocking if He grants long life to Imam Mahdi (a.t.f.s.)!
Then there is one person whose prolonged life is closely linked to Imam Mahdi (a.t.f.s.) and should put a stop to all arguments in this regard.
Prophet Khizr’s (a.s.) prolonged life
Imam Jafar Sadiq (a.s.) informed regarding Prophet Khizr (a.s.):
And as for the righteous servant, Khizr (a.s.), Allah bestowed him with a long lifespan not due to the fact that He had made him a Prophet, or because a book was revealed on him, nor because he introduced a new Shariat nullifying the previous one, nor because He made him an Imam and required the people to follow him, nor because his obedience was compulsory.
Rather, He granted Khizr (a.s.) long life because it was present in the knowledge of Allah, that during occultation, Qaim’s (a.s.) age would be prolonged to an extent that people would not believe it, and they would deny Qaim’s (a.t.f.s.) long age.
So Allah prolonged the age of the righteous servant, Khizr (a.s.) without any justification, except that it be a basis for proving the long life of Qaim (a.s.) so that the arguments and proofs of the opponents may be invalidated and that people may not have any argument against Allah’s Proof.
• Behaar al-Anwar v 51 p 222-223
After the extraordinary precedent of Prophet Khizr (a.s.), there is no case for the skeptics to deny the existence of Imam Mahdi (a.t.f.s.) on the pretext of his long life.