section_path: Abstract
section_name: Abstract
paragraph_text: Atheism, in the broadest sense, is an absence or lack of belief in the existence of gods or deities. Less broadly, atheism is a rejection of the belief that any deities exist. In an even narrower sense, atheism is specifically the position that there are no deities. Atheism is contrasted with theism, which in its most general form is the belief that at least one deity exists.
  
  Historically, evidence of atheistic viewpoints can be traced back to classical antiquity and early Indian philosophy. In the Western world, atheism declined as Christianity gained prominence. The 16th century and the Age of Enlightenment marked the resurgence of atheistic thought in Europe. Atheism achieved a significant position in the 20th century with legislation protecting freedom of thought. Broad estimates of those who have an absence of belief in a god range from 500 million to 1.1 billion people worldwide.
  
  Atheist organizations have defended the autonomy of science, secular ethics and secularism. Arguments for atheism range from philosophical to social and historical approaches. Rationales for not believing in deities include the lack of evidence, the problem of evil, the argument from inconsistent revelations, the rejection of concepts that cannot be falsified, and the argument from nonbelief.
  
  Nonbelievers contend that atheism is a more parsimonious position than theism and that everyone is born without beliefs in deities; therefore, they argue that the burden of proof lies not on the atheist to disprove the existence of gods but on the theist to provide a rationale for theism.