This article deals with the contention of whether or not the prophets and the messengers of Allah are infallible (sinless). In Part 1, we will examine the Sunni point of view, and then we will present the Shi’a opinion on the matter with reference to the verses of Qur’an. In Part 2, we will provide logical reasoning behind the issue of the infallibility. In addition, we look at some of the authentic Sunni traditions in support of the infallibility. In Part 3, we respond to the arguments of the opponents in this regard.