Christian polemicists argued the Qur’an’s own endorsements invalidate it

Evidence

The Qur’an, he continued, confirmed the authority of the earlier Testaments as prior to its own, ‘not only for the past, but for the present’. By guaranteeing the Scriptures, it invalidated itself, and yet, ‘so far as the visions of such a man could’, its confirmation of the Scripture held good. — Norman Daniel, Islam and the West, 298

Categorization

• XREF: Connects to the broader Christian-Islamic polemical tradition and how appropriation of another’s canon works as a rhetorical weapon — parallels modern apologetic moves of quoting opponents’ sources against them. — connects to: Mediaeval critics mocked the Qur’an’s chapter names as irrational; Polemics could condemn a rival religion using only its own scriptures