A Shi'ah Allaamah (scholar) was having a debate with a group of non-Shi'ah scholars.

Non-Shi'ah scholars: Why do the Shi'ah talk so much about “Imamat”, while there are many important matters in Islam, such as Salaah (prayers), Sawm (fasting), Hajj and alike?
 
Allaamah (while humbly calling Imam Ali, the Amir-Ol-Mo'menin, (PBUH) in his heart): have you heard the following Hadith (Narrative) from the Prophet Mohammad (PBUH&HP)?
 
Any one who passes away without having a profound gnosis about the “Imam” of his time, he has died, a death of Jaaheliyah (Ignorance, without Islam).
 
(Shi'ah Documents: Osool Kaafi, ...)
(Sunni Documents: Yanaabi'-Ol-Mawaddah, ...)
 
Non-Shi'ah scholars: Yes, we are familiar with this Hadith from the Prophet.
 
Allaamah: In the book “Sahih Bokhari” which is one of the most important and respected Sunni documents, there are many Narratives from the Prophet of Islam (PBUH&HP) who has said that Fatima (the Prophet's daughter) is considered the most virtuous, exalted and accepted female by Allah, both in this world and the Hereafter. Do you accept this exalted position for Fatima?
 
Non-Shi'ah scholars: That which you said is written in our books and therefore, we accept it.
 
Allaamah: In the same book, Sahih Bukhari, it has been mentioned that Fatima (PBUH) was not pleased with the first Kaliphah (governor), Abu Bakr, after her father, and she did not talk to him while she was alive. Do you verify this?
 
Non-Shi'ah scholars: Yes, that is mentioned in our books too.
 
Allaamah: If we all believe that Allah considers and accepts Fatima as the most exalted lady ever created by Him, and also, if we believe that, a person die without accepting the "Imam", will not be considered a Muslim in the Hereafter, then we must conclude that Fatima believed in an “Imam” at time of her death. Is that correct?
 
Non-Shi'ah scholars: Yes, the first Kaliphah, Abu Bakr, was her Imam.
 
Allaamah: But, according to your own documents, Fatima was not even talking to the first Kaliphah, Abu Bakr, at time of her death. Then who was her “Imam”?
 
They had nothing to say!
 
Allaamah: Yes, Fatimah's "Imam" was Ali (PBUT); this is why the Shi'ah talk so much about “Imamat”, because being a true Believer and acceptance of all deeds such as Salaah, Sawm, Hajj and …, depends on believing in “Imamat".