“[T]he Old Testament, [...] if considered as a general rule of conduct, would lead to consequences destructive of all principles of humanity and morality.”

“When principles are so absurd and so destructive of human society, it may safely be averred, that the more sincere and the more disinterested they are, they only become the more ridiculous and the more odious.”

“The admirers and followers of the Al Koran insist on the excellent moral precepts interspersed throughout that wild and absurd performance...Would we know, whether the pretended prophet had really attained a just sentiment of morality, let us attend to his narration, and we shall soon find, that he bestows praise upon such instances of treachery, inhumanity, cruelty, revenge, bigotry, as are utterly incompatible with civilised society. No steady rule of right conduct seems there to be attended to: and every action is blamed or praised, so far only as it is beneficial or harmful to the true believers.”

“There is no method of reasoning more common, and yet none more blameable, than, in philosophical disputes, to endeavour the refutation of any hypothesis, by a pretence of its dangerous consequences to religion and morality. When any opinion leads to absurdities, it is certainly false; but it is not certain that an opinion is false, because it is of danger-ous consequence. Such topics, therefore, ought entirely to be forborne; as serving nothing to the discovery of truth, but only to make the personof an antagonist odious.”

“I cannot forbear adding to these reasonings an observation, which may, perhaps, be found of some importance. In every system of morality, which I have hitherto met with, I have always remark’d, that the author proceeds for some time in the ordinary way of reasoning, and establishes the being of a God, or makes observations concerning human affairs; when of a sudden I am surpriz’d to find, that instead of the usual copulations of propositions, is, and is not, I meet with no proposition that is not connected with an ought, or an ought not. This change is imperceptible; but is, however, of the last consequence.”

“Custom, then, is the great guide of human life. It is that principle alone which renders our experience useful to us, and makes us expect, for the future, a similar train of events with those which have appeared in the past. Without the influence of custom, we should be entirely ignorant of every matter of fact beyond what is immediately present to the memory and senses. We should never know how to adjust means to ends, or to employ our natural powers in the production of any effect. There would be an end at once of all action, as well as of the chief part of speculation.”

“Men's views of things are the result of their understanding alone. Their conduct is regulated by their understanding, their temper, and their passions.”