Al-Ghazali (d. 1111) - christiansquoting.org.uk

Just as scholastic theology is used with thinking people concerning the truth, the sword is used with the infidels after informing them with the truth ... so just as it cannot be said that the sword was Mohammad's most eloquent argument, neither can it be said that scholastic theology is the ultimate science. - Ihy'a 'Uloum ed-Din by al-Ghazali, Dar al-Kotob al-'Elmeyah, Beirut, Vol. V, p. 35

…one must go on jihad (i.e., warlike razzias or raids) at least once a year...one may use a catapult against them [non-Muslims] when they are in a fortress, even if among them are women and children. One may set fire to them and/or drown them...If a person of the Ahl al-Kitab [People of The Book &endash; Jews and Christians, typically] is enslaved, his marriage is [automatically] revoked. A woman and her child taken into slavery should not be separated...One may cut down their trees...One must destroy their useless books. Jihadists may take as booty whatever they decide...they may steal as much food as they require, - Al-Ghazali (d. 1111). Kitab al-Wagiz fi fiqh madhab al-imam al-Safi'i, Beirut, 1979, pp. 186, 190-91. [English translation by Dr. Michael Schub]