Christians living under Muslim rule in 8th century Iraq had to articulate their faith and doctrines in relation to the religious and political challenges brought on by the dominating reality of Islam. The disputation between a Muslim and a monk of Bēt Ḥālē, a Christian apologetic text, is an example of one such articulation. This study places Disputation in its historical and literary context and conducts an analysis of some key Syriac terms which reveals a creative rhetorical response to a fictional representative of Islam. The study finds that the author of this work achieves a double purpose with their work. First and foremost, he defends Christian faith and practice from common Muslim objections, and ventures to challenge Islamic faith on key issues of doctrine. Secondly, he is concerned with limited but substantive gatekeeping towards other Christian confessions. Both these concerns foster a sense of distinctiveness in a time of apostasy. Still, while the primary concern of Disputation seems to be apologetics and the construction of borders, it is nevertheless a witness to the protagonists’ own border crossings with Islam and other Christian confessions. Further, the study of early Christian-Muslim relations around the interesting time and place of Disputation is indispensable to our pursuit of navigating many of the same issues more than a millennium later.