The Muslim-authored letter attributed to al-Hashimi was actually a Christian apologetic work

Evidence

Georges Tartar, in his introduction to his French translation of the Risâlat al-Kindî (Dialogue islamo-chrétien sous le Calife al-Ma’mûn, 813–834: Les épîtres d’al-Hashimî et d’al-Kindî [Paris: Nouvelles Éditions Latines, 1985], 45–61), asserts that the first letter is indeed by a Muslim. His arguments are naive and unconvincing, linked, it seems, with his own efforts to evangelize Muslims. Samir Khalil Samir, rejecting Tartar’s arguments, notes that the Risâlat borrows a section verbatim from the early ninth-century apologist Abû Râ’itah al-Takrîtî (Samir, “Earliest Arab Apology for Christianity,” 57–114; 111 n. 237); this same conclusion is reached independently by Haddad, Trinité divine, 43. — John V. Tolan, Saracens, 1554

Categorization

• XREF: Directly grounds the reader’s genealogical project on falsified/attributed dialogue texts: Christian apologists composed the ‘Muslim side’ of an interfaith debate as a straw man — an ancestor of modern polemical framing in Anidjar/Aziz.
• QUESTION: Does this falsified ‘dialogue’ structure recur in later Christian-Islamic polemical literature where one party writes both sides? Worth chasing in the genealogy.