Someone who does not believe in the existence of a god.

Roget 989: irreligion^†, indevotion^†; godlessness, ungodliness etc. adj.; laxity, quietism.    skepticism, doubt; unbelief, disbelief; incredulity, incredulousness etc. adj.^†; want of faith, want of belief; pyrrhonism; bout etc. 485; agnosticism.    atheism; deism; hylotheism^†; materialism; positivism; nihilism.    infidelity, freethinking, antichristianity^†, rationalism; neology.    [person who is not religious] atheist, skeptic, unbeliever, deist, infidel, pyrrhonist; giaour^†, heathen, alien, gentile, Nazarene; espri fort [Fr.], freethinker, latitudinarian, rationalist; materialist, positivist, nihilist, agnostic, somatist^†, theophobist^†.    ... show more

Dutch: atheïste, goddeloze, godloochenaar, atheïst
Polish: ateista, ateusz, bezwyznaniowiec, niewierzący

Related to or characterized by or given to atheism:
— Atheist leanings.

synonyms: atheistic, atheistical.

Dutch: atheïstisch
Polish: ateistyczny