One of these reasons is the difference in the religious...

One of these reasons is the difference in the religious edicts [ fatawa ] of mujtahid s and fuqaha . Their claim is that in the realm of Islam, its jurisprudence in particular, the fatawa of mujtahid s are different from each other. One mujtahid opines that the Friday congregational prayer is wajib (even during this period of major occultation [ ghaybah al-kubra ]) while another says that it is not wajib .

One decrees that playing chess is haram while another considers it halal [permissible or lawful]. One declares a certain form of music as haram while another says that it is halal . Thus, the fatawa and understandings of the fuqaha and mujtahid s are subjective, alterable and variable such that even a single mujtahid can possibly have two different religious edicts on an issue. For example, some fuaqaha give a fatwa at a given time and after sometime, they recant the said edict and issue another.

So, this difference of fatawa and understanding is a proof that our knowledge or interpretation of religion is subjective and changeable, and that it is impossible for the knowledge or understanding of religion to be fixed and absolute. We argue that everybody including an illiterate person living in a far-flung village knows that the fatawa of mujtahid s are not identical in the sphere of the branches of religion [ furu‘ad-din ] and some religious obligations.

But this difference of fatawa does not warrant you to claim that even the Apostle’s ( s ) knowledge of revelation [ wahy ] revealed to him is not absolute on the ground that the knowledge of the Apostle ( s ) also belongs to the realm of human knowledge and subject to be mistaken!

What the Apostle ( s ) has introduced to us is not the essence of divine revelation, rather a product of his knowledge and understanding of it, and since he is but human and thus fallible, it is probable that he might have erred in receiving and understanding it.