Ateizmin tarihi, ateizm düşüncesinin Antik Çağ'dan günümüze tarihini kapsayan süreçtir. Ateizm, Tanrı'nın veya tanrıların var olduğu iddiasının reddidir.[1][2][3] Diğer bir deyişle, ateizm, Tanrı veya tanrıların var olmadığı görüşünü benimser ve bu iddiaya karşı yapılan herhangi bir iddianın yanlış olduğunu savunur.[1][2][4][5]
Felsefi ateist düşünce, MÖ 6. veya 5. yüzyılda Avrupa ve Asya'da ortaya çıkmaya başladı. Antik Yunan'da, oyun yazarları tanrıların varlığı konusunda şüphelerini dile getirmekteydi ve din karşıtı felsefe okulu olan Cārvāka Antik Hindistan'da ortaya çıktı. Materyalist felsefe, MÖ 5. yüzyılda, evrendeki her şeyin boşluk içindeki atomların hareketleriyle açıklayan atomcularLeukippos ve Demokritos tarafından ortaya atıldı. Ayrıca, Aydınlanma, Avrupa'da dine karşı şüpheciliği ve laikliği körükledi.[6]
^abHarvey, Van A. Agnosticism and Atheism. in Flynn 2007: "The terms ATHEISM and AGNOSTICISM lend themselves to two different definitions. The first takes the privative a both before the Greek theos (divinity) and gnosis (to know) to mean that atheism is simply the absence of belief in the gods and agnosticism is simply lack of knowledge of some specified subject matter. The second definition takes atheism to mean the explicit denial of the existence of gods and agnosticism as the position of someone who, because the existence of gods is unknowable, suspends judgment regarding them ... The first is the more inclusive and recognizes only two alternatives: Either one believes in the gods or one does not. Consequently, there is no third alternative, as those who call themselves agnostics sometimes claim. Insofar as they lack belief, they are really atheists. Moreover, since the absence of belief is the cognitive position in which everyone is born, the burden of proof falls on those who advocate religious belief. The proponents of the second definition, by contrast, regard the first definition as too broad because it includes uninformed children along with aggressive and explicit atheists. Consequently, it is unlikely that the public will adopt it."
^ab"atheism". The Oxford Dictionary of Philosophy. 2008. Oxford University Press. 2008. ISBN978-0-19-954143-0. 12 Mart 2021 tarihinde kaynağından arşivlendi. Erişim tarihi: 21 Kasım 2013. Either the lack of belief that there exists a god, or the belief that there exists none. Sometimes thought itself to be more dogmatic than mere agnosticism, although atheists retort that everyone is an atheist about most gods, so they merely advance one step further.
^Rowe 1998: "As commonly understood, atheism is the position that affirms the nonexistence of God. So an atheist is someone who disbelieves in God, whereas a theist is someone who believes in God. Another meaning of 'atheism' is simply nonbelief in the existence of God, rather than positive belief in the nonexistence of God. ... an atheist, in the broader sense of the term, is someone who disbelieves in every form of deity, not just the God of traditional Western theology."