A twelfth-century German chronicler accurately described Muslim monotheism against lurid crusader legend

Evidence

Otto of Friesing came across the story and retells it in his Chronicle of Two Cities, but immediately rejects it as impossible: the Saracens would not have asked Thiemo to worship idols since “the Saracens universally are worshipers of one God… . They are cut off from salvation by one thing alone, that they deny that Jesus Christ … is God and the Son of God, and hold in reverence and worship as a great prophet of the Supreme God, Mahomet, a deceiver.” — John V. Tolan, Saracens, 604

Categorization

• XREF: Provides the counter-evidence that the vault’s monolithic ‘medieval Christian imaginary’ claim must accommodate: some educated clerics held essentially accurate theological knowledge of Islam within the same period.
• QUESTION: Worth chasing: how widespread was this accurate knowledge, and which genres (chronicles, disputations, polemics) tended to preserve versus suppress it?