Youssef Durrah al-Haddad, a Lebanese priest and orientalist, considers the Quran to be an adaptation of the Nazareneism. The foundation of his idea is based on “the viewpoint of adaptation” which has been investigated by other orientalists as well, with this difference that in proving his claim, he has broadly referred to the verses of the Quran. He believes that the Quran itself has admitted to be an adaptation of the Torah and the Bible. He tries to deny the autonomy of Islam as a divine religion which completes the previous religions and corrects their distortions. The present research is an attempt to elaborate and criticize al-Haddad’s views on claiming the mission of the Prophet of Islam as an adaptation of Nazareneism through documentary and qualitative analysis methodology. The research community includes the Chapter Four of the book entitled, اﻟﻘران دﻋوة اﻟﻧﺻراﻧ ﯾﺔ “The Qur’an is a Nazaritic Mission”. The findings of the research indicate that what has made Al-Haddad to consider the call of the Prophet of Islam as a Nazaritic one is his arbitrary understanding, some incorrect interpretation of phrases, lack of attention to the supplementary verses of the discussion, the register (sīyāḳ) of phrases, indifference towards the rules of Arabic literature, incorrect claim of the Quran distortion, holding a view towards Divine Revelation in disagreement with the Quran, and a claim inconsistent with the history on broad agreement of the Nazareneism with the Quranic Dawah, etc. Keywords: The Holy Quran, Mission; Muhammad, Nazareneism, Yousef Durrah al-Haddad.