Mediaeval Christian polemic relied on Scripture to refute Islam

Evidence

There was little that was fluid in a state of mind which was at least partly congealed. Much of the mediaeval attitude was destined to survive for many centuries, while other aspects were peculiarly mediaeval. These are chiefly associated with scholastic method, and here method had a share in determining substance. What was most characteristic of the mediaeval attitude to Islam was the strong dependence on Scripture, the determination to defend Scripture from any attack, and the employment of the Qur’an to defend it. — Norman Daniel, Islam and the West, 1401