Atheism refers to either the absence of a belief in the existence of deities or to an active belief that deities do not exist. This belief system rejects theology as well as the constructs of organized religion. The use of the term originated in the ancient world and was meant to degrade those who rejected commonly accepted religious precepts. It was first self-applied during the Age of Enlightenment in 18th century France. The French Revolution was driven by the prioritization of human reason over the abstract authority of religion. This prompted a period of skeptical inquiry, one in which atheism became an important cultural, philosophical, and political entity.
Many who characterize themselves as atheists argue that a lack of proof or scientific process prevents the belief in a deity. Some who refer to themselves as secular humanists have developed a code of ethics that exists separate from the worship of a deity. Determining the actual number of “practicing” atheists is quite difficult, given the absence of a unifying religious organization. Polling around the world has produced an extremely wide variance, with the largest rates of atheism generally seen in Europe and East Asia.
Closely related is the idea of agnosticism, which doesn’t profess to know whether there is or isn’t a deity. Instead, agnosticism argues that the limits of human reasoning and understanding make the existence of god(s), the origins of the universe, and the possibility of an afterlife all unknowable. Like atheism, the term emerged around the fifth century BCE and was contemplated with a particular interest in Indian cultures. It gained more popular modern visibility when coined by English biologist Thomas Henry Huxley, who in 1869 recognized the incapacity of humans to truly answer questions regarding the divine. To Huxley, and the agnostic and atheist thinkers who followed, theistic or gnostic religions lack scientific basis, and therefore, should be rejected.