“I assert, that the doctrine of the immateriality, simplicity, and indivisibility of a thinking substance is a true atheism, and will serve to justify all those sentiments, for which Spinoza is so universally infamous. From this topic, I hope at least to reap one advantage, that my adversaries will not have any pretext to render the present doctrine odious by their declamations, when they see that they can be so easily retorted on them.”

Letter X
The Nemesis of Faith (1849)

Marginalia http://www.easylit.com/poe/comtext/prose/margin.shtml (November 1844)

What then must we do? (1886)

Autobiography (1873)
Context: I thought the predominance of the aristocratic classes, the noble and the rich, in the English Constitution, an evil worth any struggle to get rid of; not on account of taxes, or any such comparatively small inconvenience, but as the great demoralizing agency in the country. Demoralizing, first, because it made the conduct of the government an example of gross public immorality, through the predominance of private over public interests in the State, and the abuse of the powers of legislation for the advantage of classes. Secondly, and in a still greater degree, because the respect of the multitude always attaching itself principally to that which, in the existing state of society, is the chief passport to power; and under English institutions, riches, hereditary or acquired, being the almost exclusive source of political importance; riches, and the signs of riches, were almost the only things really respected, and the life of the people was mainly devoted to the pursuit of them. I thought, that while the higher and richer classes held the power of government, the instruction and improvement of the mass of the people were contrary to the self-interest of those classes, because tending to render the people more powerful for throwing off the yoke: but if the democracy obtained a large, and perhaps the principal, share in the governing power, it would become the interest of the opulent classes to promote their education, in order to ward off really mischievous errors, and especially those which would lead to unjust violations of property. On these grounds I was not only as ardent as ever for democratic institutions, but earnestly hoped that Owenite, St. Simonian, and all other anti-property doctrines might spread widely among the poorer classes; not that I thought those doctrines true, or desired that they should be acted on, but in order that the higher classes might be made to see that they had more to fear from the poor when uneducated, than when educated.

The Monthly Magazine

Source: 1920s, The Future of an Illusion (1927), Ch. 6

p, 122-123
The Characteristics of the Present Age (1806)

Letter to Edward Newenham (20 October 1792) http://etext.lib.virginia.edu/etcbin/toccer-new2?id=WasFi32.xml&images=images/modeng&data=/texts/english/modeng/parsed&tag=public&part=155&division=div1, these statements and one from a previous letter to Newenham seem to have become combined and altered into a misquotation of Washington's original statements to read:
Religious controversies are always productive of more acrimony and irreconcilable hatreds than those which spring from any other cause. I had hoped that liberal and enlightened thought would have reconciled the Christians so that their religious fights would not endanger the peace of Society.
As misquoted in The Conservative Soul: How We Lost It, How to Get It Back (2006) by Andrew Sullivan, p. 131
1790s

Source: The Armor of God (1943), Ch. 1, p. 2