I shall say, that I feel myself virtuous, because my soul is at rest.

The sciences have ever been the surest guides to virtue.

it is not that religion is merely useless, it is mischievous. It is mischievous by its idle terrors; it is mischievous by its false morality; it is mischievous by its hypocrisy; by its fanaticism; by its dogmatism; by its threats; by its hopes; by its promises.

You have heard of, and studied various systems of philosophy; but real philosophy is opposed to all systems.

To give liberty to a slave before he understands its value is, perhaps, rather to impose a penalty than to bestow a blessing.

the leading error of the human mind, - the bane of human happiness - the perverter of human virtue ... is Religion - that dark coinage of trembling ignorance! It is Religion - that poisoner of human felicity! It is Religion - that blind guide of human reason! It is Religion - that dethroner of human virtue! which lies at the root of all the evil and all the misery that pervade the world!

... the yearly expenses of the existing religious systemexceed in these United States twenty millions of dollars. Twenty millions! For teaching what? Things unseen and causes unknown!... Twenty millions would more than suffice to make us wise; and alas! do they not more than suffice to make us foolish?