This study aims at elucidating and clarifying Islam's position towards orientalists' opinions concerning the infallibility of the Prophet Mohammad Peace and Prayers by Upon Him (PPUH) in his acts and diligence (ijtihad) through investigating the orientalist literature and resources in which the suspicions occurred are related to the research subject. Then analyze and criticize those suspicions by referring to Islamic authenticity sources. The research concluded that the claims of orientalism collapsed in the face of the absence of logical and written evidences concerning the subject of infallibility. The research also recommended the importance of paying attention to orientalist studies and intensifying the efforts to overcome these suspicions with thought, study and research.