“It is an open question whether any behavior based on fear of eternal punishment can be regarded as ethical or should be regarded as merely cowardly.”

Through a Window: My Thirty Years with the Chimpanzees of Gombe (2000), p. 245

Kantian Ethics (2008)

Interview by Alec Mouhibian in The Free Radical (November 2004) http://rebirthofreason.com/Articles/Mouhibian/Nathaniel_Branden_Interview,_Pt_3.shtml
Context: One of the mistakes that Rand makes is that after she condemns a belief or an action, she goes on to tell you the psychology of the person who did it, as if she knows. I focus my judgment on the action and not on the person. My primary interest is: do I admire or dislike this behavior? And there, judgment is important for me. People often attribute all kinds of things to another person, without ever knowing where that person’s coming from. Most of the time, I regard the judgment of people as a waste of time. I regard the judgment of behavior as imperative.

Source: Man for Himself (1947), Ch. 3
Context: Temperament refers to the mode of reaction and is constitutional and not changeable; character is essentially formed by a person’s experiences, especially of those in early life, and changeable, to some extent, by insights and new kinds of experiences. If a person has a choleric temperament, for instance, his mode of reaction is "quick and strong.” But what he is quick or strong about depends on his kind of relatedness, his character. If he is a productive, just, loving person he will react quickly and strongly when he loves, when he is enraged by injustice, and when he is impressed by a new idea. If he is a destructive or sadistic character, he will be quick and strong in his destructiveness or in his cruelty. The confusion between temperament and character has had serious consequences for ethical theory. Preferences with regard to differences in temperament are mere matters of subjective taste. But differences in character are ethically of the most fundamental importance.

Pamphilus to Hermippus, Prologue
Dialogues Concerning Natural Religion (1779)

Source: On Liberty (1859), Ch. 1: Introductory

Progress, Coexistence and Intellectual Freedom (1968)
Context: We regard as "scientific" a method based on deep analysis of facts, theories, and views, presupposing unprejudiced, unfearing open discussion and conclusions. The complexity and diversity of all the phenomena of modern life, the great possibilities and dangers linked with the scientific-technical revolution and with a number of social tendencies demand precisely such an approach, as has been acknowledged in a number of official statements.

Wording in Ideas and Opinions: The man who is thoroughly convinced of the universal operation of the law of causation cannot for a moment entertain the idea of a being who interferes in the course of events — provided, of course, that he takes the hypothesis of causality really seriously. He has no use for the religion of fear and equally little for social or moral religion. A God who rewards and punishes is inconceivable to him for the simple reason that a man's actions are determined by necessity, external and internal, so that in God's eyes he cannot be responsible, any more than an inanimate object is responsible for the motions it undergoes. Science has therefore been charged with undermining morality, but the charge is unjust. A man's ethical behavior should be based effectually on sympathy, education, and social ties and needs; no religious basis is necessary. Man would indeed be in a poor way if he had to be restrained by fear of punishment and hopes of reward after death.
Variant: "It seems to me that the idea of a personal God is an anthropological concept which I cannot take seriously. I also cannot imagine some will or goal outside the human sphere" has been cited http://www.positiveatheism.org/hist/quotes/einstein.htm as a statement that precedes the last three sentences here, but in fact this is a separate quote from a 1947 letter Einstein wrote to Murray W. Gross, included in the Einstein and Religion (1999) section below (and in the letter the word used is "anthropomorphic," not "anthropological").
1930s, Religion and Science (1930)
Context: For any one who is pervaded with the sense of causal law in all that happens, who accepts in real earnest the assumption of causality, the idea of Being who interferes with the sequence of events in the world is absolutely impossible. Neither the religion of fear nor the social-moral religion can have any hold on him. A God who rewards and punishes is for him unthinkable, because man acts in accordance with an inner and outer necessity, and would, in the eyes of God, be as little responsible as an inanimate object is for the movements which it makes. Science, in consequence, has been accused of undermining morals—but wrongly. The ethical behavior of man is better based on sympathy, education and social relationships, and requires no support from religion. Man's plight would, indeed, be sad if he had to be kept in order through fear of punishment and hope of rewards after death.

p. 11 of "Comments on the foundations of set theory." https://books.google.com/books?id=TVi2AwAAQBAJ&pg=PA11 In Axiomatic set theory, pp. 9-15. Providence (RI). American Mathematical Society, 1971.