The term New Atheism describes the positions of some atheist academics, writers, scientists, and philosophers of the 20th and 21st centuries. New Atheism advocates the view that superstition, religion, and irrationalism should not simply be tolerated. Instead, they advocate the antitheist view that the various forms of theism should be criticised, countered, examined, and challenged by rational argument, especially when they exert strong influence on the broader society, such as in government, education, and politics. Major figures of New Atheism include Richard Dawkins, Sam Harris, Christopher Hitchens, and Daniel Dennett, collectively referred to as the "Four Horsemen" of the movement, as well as Ayaan Hirsi Ali, until her conversion to Christianity in 2023.

Criticism of religion involves criticism of the validity, concept, or ideas of religion. Historical records of criticism of religion go back to at least 5th century BCE in ancient Greece, in Athens specifically, with Diagoras "the Atheist" of Melos. In ancient Rome, an early known example is Lucretius' De rerum natura from the 1st century BCE.