1) Well, he was an illiterate "diplomat, merchant, philosopher, orator, legislator, reformer, military general". Not so bad, isn't it? Source and further information: http://en.wikipedia.org/wiki/Muhammad 2) "The Qur’an states that Muhammad was ummi, interpreted as illiterate in Muslim tradition. According to Watt, the meaning of the Qur’anic term ummi is unscriptured rather than illiterate. Watt argues that a certain amount of writing was necessary for Muhammad to perform his commercial duties though it seems certain that he had not read any scriptures." Source and further information: http://en.wikipedia.org/wiki/Qur'an 3) "Muslim scholars believe that prophet Muhammad was an illiterate, as mentioned in the Quran itself, "Those who follow the messenger, the Prophet who can neither read nor write, whom they will find described in the Torah and the Gospel (which are) with them......"Quran 7:157. However, the Arabic word translated here as 'illiterate' also means 'gentile'. He would memorize the Qur'an by ear, and later recite it to his companions, who also memorized it. Before the Qur'an was written down, speaking it from memory prevailed as the mode of teaching it to others. This fact, taken in the context of seventh century Arabia, was not at all an extraordinary feat. People of that time had a penchant for recited poetry and had developed their skills in memorization to a remarkable degree. Events and competitions that featured the recitation of elaborate poetry were of great interest. Some scholars, like William Montgomery Watt and Maxime Rodinson believe that Muhammad was literate and educated." Source and further information: http://en.wikipedia.org/wiki/History_of_the_Qur'an

the point is to send an illiterate prophet .. to prove to people that he didn't write it but revealed from Allah.