The idolaters and polytheists of Mekkah proved that they were not truthful for they broke the peace treaty (i.e. Hudaybiyyah) that they made with Muslims, an act that eventually led to the conquest of Makkah by the Prophet and his followers. Thus, as the threat still existed and it is very much likely that the polytheists would work on a plot against Muslims if they had an opportunity. So the Qur'an commands Muslims to leave any contracts they had with polytheists. Actually, any probable threat must be prevented, and the contracts that Muslims had with polytheists guaranteed the presence of polytheists in Makkah, so the idolaters were able to make a plan against Muslims. Although, Islam generally commands Muslims to hold their contracts and treaties it, also, commands them to protect themselves as well. The Qur'an gave the idolaters enough time (i.e. four months) to become Muslim or leave the city. The Qur'an did not force them to be a Muslim and gave them plenty of time to ponder and think. The Qur'an, actually, did not attack idolaters without prior notice.
