Abu al-Hasan 'Ali ibn Rabban al-Tabari was a Christian convert to Islam who subsequently became a table companion of the Abbasid Caliph, al-Mutawakkil and the previous caliphs. Known as an expert in medicine, his professional background was described variously as a 'Christian writer' (al-Katib al-Nasrani), the secretary of Governor Mazyar ibn Qarin (katib Mazyar) (Ibn Maskawayh 2000), and also a medical doctor (al-Tabib). Al-Qifti attributed him as an authority in medical sciences, an expert in philosophy, a devotee of the natural sciences (Al-Qifti, 2005). His considerable abilities as an administrative secretary and writer testify to his ability or, indeed, probable mastery of the Arabic language, which would have helped him greatly in his understanding the meaning and interpretation of the Quran.Early Muslim sources frequently associate Ibn Rabban's name with his former Christian belief. Christian titles such al-Nasrani and Masihi (Ibn Nasir al-Din 1993) evidently accompanied his name. In fact, in his work, al-Radd 'ala al-Nasara, he openly acknowledges his first seventy year of life as a Christian, as he does in respect of his book al-Din wa al-Dawla, in which he clearly concedes his Christian origins (Ibn Rabban 1992). It is undeniable that his uncle, Abu Zakaria Yahya ibn al-Nu'man, a prominent Christian scholar and expert in debate, is likely to be the source of his Christian and theological knowledge. In discussions of the polemical topic of the authenticity of the Quran and the signs of prophethood, he quotes twice his uncle's own words as his source of information. This implies that he was no ordinary Christian, but that he was nurtured in a family with a thoughtful Christian faith.From Christianity to IslamAccording to Ibn al-Nadim (1997), Ibn Rabban's conversion to Islam occurred in the reign of al-Mu'tasim. However, the warmth of the statement which he makes regarding Caliph al-Mutawakkil in his work al-Din wa al-Dawla leads A. Nuwayhid and David Thomas to suggest that he converted in the period of al-Mutawakkil (Thomas 2015). Meyerhof (1931) offers other evidence for the date of his conversion. Based on his reading, Ibn Rabban produced his medical treatise entitled Firdaws al-Hikma eight years after the death of al-Mu'tasim; and since there is no Quranic citation and 'Muhammedan sentences' in the work, he argues that Ibn Rabban's conversion could not have occurred in the reign of al-Mu'tasim and suggests that its happened in the era of al-Mutawakkil. In contrast, Bouyges asserts that the absence of Islamic language and references in Firdaws does not prove that he was not Muslim at the time he composed the book (Adang 1996).What galvanized him to convert to Islam is left tantalizingly unclear. Adang (1996) adduces three modern scholars' opinions regarding this. According to her, Ibn Rabban's conversion seems to be attributed to ulterior motives; whereas Noldeke conceives him as an opportunist; Macdonald identifies his conversion as nominal and professional; while Meyerhof (1931) suggests that it was Caliph's pressure that influenced his conversion. Since there is no clear statement or confession regarding his conversion, these theories remain conjecture. Even though his conversion came late in his life, after seventy years of life as a Christian, his acquaintance and contact with the Quran and Islamic knowledge appears to have occurred long before his conversion, while he was still a practicing Christian. In conversation between him and his uncle regarding rhetorical aspects of the Quran and the miracles of the Prophet, Ibn Rabban acknowledges freely that such discussions took place while he was a practising Christian.Physician by ProfessionThe focus of the greater part of Ibn Rabban al-Tabari's works concern knowledge of medical and health sciences; and as a result, al-Dhahabi (1985) called him 'the author of medical works' (sahib al-tasanif al-tibbiyah). Twelve titles of his works are recorded by Ibn al-Nadim, Ibn al- Qifti, Ibn Abi Usaybi'a and Ibn Isfandiyar, and three of them were published (Thomas 2015). …