Medieval Christian writers defined Muhammad’s teaching chiefly as denial of the Trinity.

Evidence

Guibert thought that it was the first thing popularly attributed to Muhammad; and much later Fitzralph was to characterise ‘this pseudoprophet … whose attempt was always and above all things to persuade (men) that there is no Trinity of Persons in God, and that Christ was not God’. This was almost the definition of Muhammad’s teaching … It was general to put the denial of the Trinity at the beginning of any account of Islamic teaching. — Norman Daniel, Islam and the West, 970

Categorization

• XREF: Related to the theme in Daniel’s Islam and the West — medieval polemic framed Islam primarily through the Trinity/Christology lens rather than through law or ethics. — connects to: Muslims rejected the Trinity as polytheism and carnal generation