“They say: ‘Why were Signs from his Lord not sent down upon him?’ Say: ‘The Signs are only with Allah. As for me, I am no more than a plain warner.’ Does it not suffice for them (as a Sign) that We revealed to you the Book that is recited to them? Surely there is mercy and good counsel in it for those who believe.” (Al Qur’ān – 29:50-51)
These ayahs mean to say: Is the revelation of a Scripture like the Qur’ān to an unlettered person not enough of a miracle to persuade people to believe in Muhammad’s Messengership? Is any further proof needed? Moreover, tangible miracles are effective for those who directly experience them, and, hence, their impact has a temporal dimension. This, however, does not apply to the Qur’ān. This living miracle is and will always remain before people’s eyes. Furthermore, it is recited to them day in and day out.
In face of this explicit Qur’ānic statement about the unletteredness of the Prophet Muhammad (peace and blessings of Allah be to him), one can only express astonishment at the audacity of those who seek to project him as literate. They do so while the Qur’ān specifically identifies him as unlettered precisely because this is a powerful argument in support of his Messengership’s genuineness.
As for reports that claim that he was literate or that he had acquired literacy at a later stage, these too should be dismissed out of hand. Any report contrary to the Qur’ān is, in fact, not even worth considering.