This article focuses on Al-Azmeh’s conjoined work on Arabian polytheism and the changes it went through under the Roman Empire and the ecumenism it permitted, whence he draws inferences on the origin of the term Allāh. A study of textual sources from the Najrān area is effected in order to check the validity of Al-Azmeh’s claims. Such sources reveal first that the term al-ʾIlāh appeared in texts from the 5th and 6th centuries, in reference to the God of Christianity. Secondly, they show that certain Syriac texts use the name Allāh as the God of Christians who suffered a massacre in the area. Finally, they uncover the use of the term al-Lāh, used in reference to a polytheistic god venerated in that same region. This triple revelation constitutes the basis for a nuanced reading of Al-Azmeh’s thesis.