Despite of being a small religious sect, the Mandaeans, in the period of the rise and spread of Christianity or after the rise of Islam, especially after emerging of Arab and Islamic civilization during the Abbasid period, in the development of spiritual and intellectual life in Mesopotamia and the lands where They did, they played a prominent role, and among them brilliant scientific personalities made a great contribution to the promotion of Arab and Islamic civilization. Unfortunately, in spite of mentioning the religion of some other writers of their time, the historians have limited themselves to the biography and mention of their literature and sciences, without mentioning their religion; but this is acceptable because of the Mandaeans' insistence on keeping secret or the fear of announcing their religion or the lack of transparency in the philosophy of this religion. The findings of the present article show that there were Mandaeans personalities who had a valuable contribution to Islamic civilization and culture, and some of them became Muslims later, which were not addressed in previous research. The study seeks to find the influence and role of the intellectuals of this religious sect in promoting different cultures and sciences and ethics for the development of spiritual and intellectual life in the lands of their residence through descriptive – analytical and library methods in collecting data.