“My mother was convinced, and on this head I have retained her firm belief, that to kill animals for the purpose of feeding on their flesh is one of the most deplorable and shameful infirmities of the human state; that it is one of those curses cast upon man either by his fall, or by the obduracy of his own perversity. She believed, and I am of the same belief, that these habits of hard-heartedness towards the gentlest animals, our companions, our auxiliaries, our brethren in toil and even in affection here below; that these immolations, these sanguinary appetites, this sight of palpitating flesh, are calculated to brutalize the instincts of the heart and make them ferocious. She believed, and I am of the same belief, that this nurture, which is seemingly much more succulent and much more energetic, contains in itself active causes of irritation and putridity, which sour the blood and shorten the days of mankind. In support of these ideas of abstinence, she quoted the innumerable gentle and pious tribes of India who deny themselves all that has had life; and the strong and healthy races of the shepherds and even of the laboring classes of our fields.”

Source: Mind is a Myth (1987), Ch. 1: The Certainty That Blasts Everything

Explaining his refusal to sign a "National Day of Prayer" proclamation (6 May 1999)
Context: I believe in the separation of church and state... We all have our own religious beliefs. There are people out there who are atheists, who don't believe at all... They are all citizens of Minnesota and I have to respect that.

Of the Origin and Progress of Language (Edinburgh and London: J. Balfour and T. Cadell, 2nd ed., 1774), Vol. I, Book II, Ch. II, pp. 224-225 https://archive.org/stream/originandprogre01conggoog#page/n251/mode/2up.

Source: The Economic Problem (1925), Chapter I, "The Problem Profounded", p. 1

Source: Life Itself : A Memoir (2011), Ch. 54 : How I Believe In God
Context: I have no patience for churches that evangelize aggressively. I have no interest in being instructed in what I must do to be saved. I prefer vertical prayer, directed up toward heaven, rather than horizontal prayer, directed sideways toward me. I believe a worthy church must grow through attraction, not promotion. I am wary of zealotry; even as a child I was suspicious of those who, as I often heard, were “more Catholic than the pope.” If we are to love our neighbors as ourselves, we must regard their beliefs with the same respect our own deserve.

Source: 1950s, Unpopular Essays (1950)

Source: Speaker for the Dead

Source: 1940s, A History of Western Philosophy (1945), Chapter XXXI "The Philosophy of Logical Analysis"