The fact is, the great intellectuals of the western religious tradition from Augustine to Aquinas and Peter Abelard became philosophically dominant. The intellectual tradition was preserved. The great intellectuals of the Islamic tradition like Averroes and Avicenna became heretics whose influence disappeared under the weight of rote preaching and practice. Islam as a result has a moral code, a legalistic system of right and wrong, but no evolved ethical tradition.
R. Joseph Hoffmann
aquinas, catholic, ethics, islam, morality