Premodern Christian polemics staged Muslims as easily-convinced strawmen

Evidence

His Dzalogus is realistic enough at the beginning, when the Muslim protagonist asks why Christians speak so ill of Muhammad, who speaks so well of Christ; and, throughout, the Muslim is allowed to make some good points against his opponent; but he is far too easily persuaded that the Qur’ain ‘has been corrupted by evil men’, and by the end he has been wholly, and most improbably, converted. — Norman Daniel, Islam and the West, 1551