The knowledge of God is the cause of things. For the knowledge of God is to all creatures what the knowledge of the artificer is to things made by his art.
Thomas AquinasHe (Mohammed) seduced the people by promises of carnal pleasure to which the concupiscence of the flesh urges us. His teaching also contained precepts that were in conformity with his promises, and he gave free rein to carnal pleasure. In all this, as is not unexpected; he was obeyed by carnal men. As for proofs of the truth of his doctrine, he brought forward only such as could be grasped by the natural ability of anyone with a very modest wisdom. Indeed, the truths that he taught he mingled with many fables and with doctrines of the greatest falsity.
Thomas AquinasIn questions of this sort there are two things to be observed. First, that the truth of the Scriptures be inviolably maintained. Secondly, since Scripture doth admit of diverse interpretations, that no one cling to any particular exposition with such pertinacity that, if what he supposed to be the teaching of Scripture should afterward turn out to be clearly false, he should nevertheless still presume to put it forward, lest thereby the sacred Scriptures should be exposed to the derision of unbelievers and the way of salvation should be closed to them.
Thomas Aquinas