• List of irreligious organizations

A

• Allianz vun Humanisten, Atheisten an Agnostiker
• American Association for the Advancement of Atheism
• American Atheists
• American Humanist Association
• Anti-Persecution Union
• Association of Atheists and Freethinkers
• Association of Black Humanists
• Atheism Association (Turkey)
• The Atheist Agenda
• Atheist Alliance International
• Atheist Centre
• Atheist Democracy
• Atheist Foundation of Australia
• Atheist Ireland
• Atheist Republic
• Atheist Union of Greece
• Atheists In Kenya Society
• Atheists of Florida
• Ayn Rand Institute

B

• Brazilian Association of Atheists and Agnostics

C

• Center for Inquiry
• Central Secular Council
• Centre for Inquiry Canada
• Charles E. Stevens American Atheist Library and Archives
• The Clergy Project
• Company of Propagation of Secular Culture

D

• Danish Atheist Society

E

• Ex-Muslims of North America

F

• Faith to Faithless
• Foundation Beyond Belief
• Freedom From Religion Foundation
• Freethinking Atheist and Agnostic Kinship

H

• Humanist Association of Ireland
• Humanist Canada
• Humanists International

I

• The Institute for Research of social awareness and scientific atheism of Czechoslovak Academy of Sciences
• Institute of Scientific Atheism
• International League of Non-Religious and Atheists
• Internet Infidels

L

• League of Militant Atheists
• Leeds Atheist Society

M

• Maharashtra Rationalist Association
• Military Association of Atheists and Freethinkers
• Mouvement laïque québécois
• Mythicist Milwaukee

N

• National Secular Society
• Neo-Communist Party of the Soviet Union
• Norwegian Heathen Society

P

• Philippine Atheism, Agnosticism, and Secularism Inc.
• Polish Association of Free Thought

R

• Rational Response Squad
• Rationalist International
• Recovering from Religion

S

• Secular Student Alliance
• Sunday Assembly

T

• Tatar Union of the Godless

U

• Union of Freethinkers of Finland
• Union of Rationalist Atheists and Agnostics

V

• De Vrije Gedachte