Prophet Mohammad (PBUH) has always recommended the pious to be faithful to the Islamic ethics and behave fairly toward all people. Quranic verses and hadiths of Ahl-ol-Bayt all emphasize on the fact that even in the face of heretical people and movements, justice and morality should not be violated and moreover religion should never be defended employing deceitful and rebuking ways. But in the recent era, a theory has emerged that validates attributing lies to some of the religious opponents (heretics) by means of defaming them in order to prevent people from been deceived by them. This theory‘s main argument is a narration known as “Mobahata” (calumniation) along with other acclaimed evidences. The present study with critical –analytical reconsideration of the aforementioned narration as well as other reasons did not find the provided documentations sufficient to prove the theory and authoritative enough for specifying the general rules mentioned in religious sources against such conduct. Consequently the author believes that Islamic doctrine never justifies these kinds of behaviors.