“The barbarities and desperate outrages of the so-called Christian race, throughout every region of the world, and upon every people they have been able to subdue, are not to be paralleled by those of any other race, however fierce, however untaught, and however reckless of mercy and of shame in any age of the earth.”

Interview in Speaking of Science Fiction: The Paul Walker Interviews (1978)
Context: When I talk of the purpose of life, I am thinking not only of human life, but of all life on Earth and of the life which must exist upon other planets throughout the universe. It is only of life on Earth, however, that one can speak with any certainty. It seems to me that all life on Earth, the sum total of life upon the Earth, has purpose. If the means were available, we could trace our ancestry — yours and mine — back to the first blob of life-like material that came into being on the planet. The same thing could be done for the spider that spun his web in the grass, and of the grass in which the web was spun, the bird sitting in the tree and the tree in which he sits, the toad waiting for the fly beneath the bush, and for the fly and bush. We are all genetic brothers. The chain of life, tracing back to that primordial day of life's beginning, is unbroken...

The Autobiography of an Ex-Colored Man, ch. 10.

"What I Believe" in The Forum 84 (September 1930), p. 139; some of these expressions were also used separately in other Mencken essays.
1930s
Context: I believe that religion, generally speaking, has been a curse to mankind — that its modest and greatly overestimated services on the ethical side have been more than overcome by the damage it has done to clear and honest thinking.
I believe that no discovery of fact, however trivial, can be wholly useless to the race, and that no trumpeting of falsehood, however virtuous in intent, can be anything but vicious.
I believe that all government is evil, in that all government must necessarily make war upon liberty and the democratic form is as bad as any of the other forms.
I believe that the evidence for immortality is no better than the evidence of witches, and deserves no more respect.
I believe in the complete freedom of thought and speech — alike for the humblest man and the mightiest, and in the utmost freedom of conduct that is consistent with living in organized society.
I believe in the capacity of man to conquer his world, and to find out what it is made of, and how it is run.
I believe in the reality of progress.
I —But the whole thing, after all, may be put very simply. I believe that it is better to tell the truth than to lie. I believe that it is better to be free than to be a slave. And I believe that it is better to know than be ignorant.

Seventy Thousand Assyrians (1934)

"French Letters: The Theory of the New Novel," http://books.google.com/books?id=U_YmAQAAIAAJ&q=%22It+is+the+spirit+of+the+age+to+believe+that+any+fact+no+matter+how+suspect+is+superior+to+any+imaginative+exercise+no+matter+how+true%22&pg=PA317#v=onepage Encounter magazine (December 1967)
"French Letters: Theories of the New Novel," http://books.google.com/books?id=T4lBAAAAIAAJ&q=%22It+is+the+spirit+of+the+age+to+believe+that+any+fact+no+matter+how+suspect+is+superior+to+any+imaginative+exercise+no+matter+how+true%22&pg=PA24#v=onepage Reflections Upon a Sinking Ship (1969)
1960s

[ Link to tweet https://twitter.com/dril/status/235218148800991233]
Tweets by year, 2012

Letter to his wife, Mary Anne Lee http://www.fair-use.org/robert-e-lee/letter-to-his-wife-on-slavery (27 December 1856)
1850s
Context: In this enlightened age, there are few I believe, but what will acknowledge, that slavery as an institution, is a moral & political evil in any Country. It is useless to expatiate on its disadvantages. I think it however a greater evil to the white man than to the black race, & while my feelings are strongly enlisted in behalf of the latter, my sympathies are more strong for the former. The blacks are immeasurably better off here than in Africa, morally, socially & physically. The painful discipline they are undergoing, is necessary for their instruction as a race, & I hope will prepare & lead them to better things. How long their subjugation may be necessary is known & ordered by a wise Merciful Providence.

"If Hitler Were Alive, Whose Side Would He Be On?" in M.S. magazine (October-November 1980); later in Outrageous Acts and Everyday Rebellions (1983)
Context: However sugarcoated and ambiguous, every form of authoritarianism must start with a belief in some group's greater right to power, whether that right is justified by sex, race, class, religion or all four. However far it may expand, the progression inevitably rests on unequal power and airtight roles within the family.

Interview with Louis Theroux on Weird Weekends (2 June 1999)