- Religion : Belief in, and systems of, worshipful dedication to a superhuman power or belief in the ultimate nature of existence.
- Discrimination against atheism : Add brief definition or description
- Naturalism : A concept with the view that ultimately nothing resists explanation by the methods characteristic of the natural sciences.
- Problem of evil : Add brief definition or description
Prominent deceased atheists
- Diagoras : Add brief definition or description
- Critias : A dialogue of Plato.
- Leucippus : Add brief definition or description
- Democritus : (c. 494 - c. 404 BC) Greek natural philosopher who promulgated the atomic theory, which asserted that the universe is composed of two elements: the atoms and the void in which they exist and move.
- Baron d'Holbach : Add brief definition or description
- Karl Marx : 19th century philosopher and economist. Creator of a theoretical foundation for Communism.
- Arthur Schopenhauer : (1788-1860) German philosopher, author of Die Welt als Wille und Vorstellung (1819 und 1844) (The World as Will and Representation/Idea).
- Friedrich Nietzsche : (1844–1900) German philosopher and writer who developed key concepts of morality, religion and the contemporary culture of Europe.
- Bertrand Russell : (1872–1970) British analytic philosopher, logician, essayist and political activist.
- Sigmund Freud : (1856 – 1939) Pioneering psychiatrist who developed psychoanalysis.
- Clarence Darrow : Infamous American lawyer who defended John Scopes, the teacher in the Scopes Monkey Trial, and the murderers Leopold and Loeb.
- Ayn Rand : (1905-82) Russian-born novelist, nowadays credited as the founder of the philosophical movement called Objectivism; wrote Atlas Shrugged, The Fountainhead etc
- Richard Feynman : (1918–1988) An American physicist known for his scientific acumen, humor, and charismatic charm; drummer and painter of scandalous paintings; member of the Presidential Commission on the Space Shuttle Challenger Accident, then Professor of Theoretical Physics at California Institute of Technology; Nobel Prize winner in Physics, 1965; staff, Manhattan Project
- Carl Sagan : Add brief definition or description
- Douglas Adams : (1952–2001) English author, comic radio dramatist, and musician, best known as the author of The Hitchhiker's Guide to the Galaxy.
- Bruce Lee : Chinese martial arts artist and movie actor.
Prominent living atheists
- Julian Baggini : Add brief definition or description
- David Chalmers : Add brief definition or description
- Richard Dawkins : British ethologist, evolutionary biologist; writer and broadcaster on science and atheism (born 1941).
- Daniel Dennett : Add brief definition or description
- Sam Harris : Add brief definition or description
- Stephen Hawking : Add brief definition or description
- Christopher Hitchens : Author, journalist and literary critic, perhaps best known for his writings on religion and atheism, and his defence of the Iraq War; contributing editor, Vanity Fair; columnist, The Atlantic; advisory board, Secular Coalition for America (1949-2011).
- Colin McGinn : Add brief definition or description
- Michel Onfray : Add brief definition or description
- John Searle : Add brief definition or description
- Agnosticism : The position that is not possible to have knowledge of God.
- God : Supreme, supernatural entity, often credited with omnipotence, omniscience and rulership of the universe.
- Humanism : A group of ethical theories that place the human being at the center of our moral concern. Also, an intellectual trend towards such ethical theories that occurred in the Western Renaissance and Reformation.
- Secularism : The idea that government should exist separately from religion.
- Theism : Add brief definition or description