According to the commander of the faithful, Imam Ali (peace be upon him) the mission of the Messenger of Allah (PBUH) was announcing the divine religion among the people whose no aspects of their lifestyles were proper. The following is the exact statement of the commander of the faithful: the holy prophet was appointed to the prophetic mission by Allah in an age that the relationship of people was completely cut with prophecy, and the effects of the past Ulu'l-Azm Prophets ( the prophets with books and divine religious laws) were not seen among people either. He was appointed for the prophetic mission among such savage, violent, wicked people with perverted thoughts and wrong customs and traditions so that he rebuilds this dilapidated foundation of humanity.
source : erfan.ir