This study explores the distinctive features of Fatimid ideology and propaganda, as demonstrated in the largest and most notable mosque of this era, built in Cairo during the Fatimid period (909-1171 AD). It specifically examines the numerous Quranic inscriptions decorating various parts of the mosque. These inscriptions are scrutinized in light of Arabic theosophic writings from the same period. This study also highlights the mosque's significance as a primary medium for Fatimid propaganda (da'wa), aimed at disseminating Fatimid religious ideology throughout the Islamic world. A substantial part of this work is dedicated to the figure of Imam al-akim, who played a key role in the completion of the mosque bearing his name and was revered as a divine representative on Earth.