Ateis atau Ateisme iolah sabuah pandangan filosofi nan picayo indak adonyo kabaradoan Tuhan jo dewa-dewi[1] atau juo penolakan tahadok teisme nan disaratoi jo klaim.[2][3] Dalam pangartian nan paliang lueh, itu adolah kapicayoan soal indak adonyo dewa atau Tuhan.[4][5]
Panulih Parancih abaik ka-18, Baron d'Holbach adolah salah saurang nan mulo-mulo nan manyabuik dirinyo ateis. Dalam buku Système de la Nature (1770), inyo malukihkan jagaik raya dalam arati materialisme filsafat, determinisme nan sampiik, dan ateisme. Buku iko dan bukunyo Common Sense (1772) dikutuak dek Parlemen Paris, dan salinan-salinannyo dibaka di muko umum.
Istilah ateisme barasa dari bahaso Yunani ἄθεος (átheos), nan sacaro peyoratif digunoan untuak marujuak pado siapopun nan kapicayoan batantangan jo agamo/kapicayoan nan alah mapan di lingkuangannyo. Dek manyebarnyo pamikiran bebas, skeptisisme ilmiah, jo kritik tahadok agama, istilah ateis mulai dispesifikasi untuak marujuak kapado mereka nan indak picayo kapado Tuhan. Urang nan partamo kali mangaku sabagai "ateis" muncua pado abad ka-18. Pado zaman kini, sakitar 2,3% populasi dunia mangaku sabagai ateis, manokalo 11,9% mangaku sabagai nonteis.[6] Sakitar 65% penduduak Japang mangaku sabagai ateis, agnostik, atau juo urang nanindak baagamo; jo sakitar 48%-nyo di Rusia.[7] Persentase komunitas tasabuik di Uni Eropa bakisar antaro 6% (Italia) sampai 85% (Swedia).[7]
Banyak ateis basikap skeptis kapado kabaradoan fenomena paranormal karano kurangnyo bukti empiris. Nan lain maagiah argumen jo dasar filosofis, sosial, atau sijarah.
Pado kabudayoan Barat, ateis acok kali diasumsian sabagai indak baagamo (ireligius). Beberapa aliran Agamo Buddha indak panah manyabuikkan istilah 'Tuhan' dalam babagai upacara ritual, tapi dalam Agama Buddha konsep ketuhanan nan dimaksuik mampagunokan istilah Nirwana.[8] Karanonyo agamo iko acok disabuik agamo ateistik.[9] Walaupun banyak dari nan mandefinisikan dirinyo sabagai ateis candoang kapado filosofi sekuler cando humanisme,[10]rasionalisme, dan naturalisme,[11] indak ado ideologi atau perilaku spesifik nan dijunjuang dek sadoalah ateis.[12]
Nielsen,Kai(2009)."Atheism".Encyclopædia Britannica.http://www.britannica.com/EBchecked/topic/40634/atheism.Diakses pado 28 April 2007. "Atheism, in general, the critique and denial of metaphysical beliefs in God or spiritual beings.... a more adequate characterization of atheism consists in the more complex claim that to be an atheist is to be someone who rejects belief in God for [reasons that depend] on how God is being conceived."
Edwards,Paul(1967)."Atheism".The Encyclopedia of Philosophy.Vol. 1.Collier-MacMillan.p.175."On our definition, an 'atheist' is a person who rejects belief in God, regardless of whether or not his reason for the rejection is the claim that 'God exists' expresses a false proposition. People frequently adopt an attitude of rejection toward a position for reasons other than that it is a false proposition. It is common among contemporary philosophers, and indeed it was not uncommon in earlier centuries, to reject positions on the ground that they are meaningless. Sometimes, too, a theory is rejected on such grounds as that it is sterile or redundant or capricious, and there are many other considerations which in certain contexts are generally agreed to constitute good grounds for rejecting an assertion.".
Artikel pendek religioustolerance.org pada Definitions of the term "Atheism"Archived 2020-01-02 di Wayback Machine. menyatakan bahwa tidak ada konsensus mengenai definisi istilah ateisme. Simon Blackburn pada The Oxford Dictionary of Philosophy: "Atheism. Either the lack of belief in a god, or the belief that there is none".
Runes,Dagobert D.(editor)(1942 edition).Dictionary of Philosophy.New Jersey:Littlefield, Adams & Co. Philosophical Library.ISBN0064634612.http://www.ditext.com/runes/a.html.Diakses pado 1 Pebruari 2010."(a) the belief that there is no God; (b) Some philosophers have been called "atheistic" because they have not held to a belief in a personal God. Atheism in this sense means "not theistic". The former meaning of the term is a literal rendering. The latter meaning is a less rigorous use of the term though widely current in the history of thought"