'anti-theistic' originates from Greek and Modern English components: the prefix 'anti-' from Ancient Greek 'antí' meaning 'against', combined with 'theistic', built from 'theism' (Modern English/New Latin) ultimately from Greek 'theos' meaning 'god'.

'anti-theistic' was formed in English by combining 'anti-' + 'theistic' (the latter from 'theism' + adjectival '-ic'); it developed from earlier formations such as 'antitheism' and 'antitheist' in the 18th–19th centuries and later took adjectival form 'anti-theistic'.

Initially and historically it meant simply 'against theism'; over time the term has retained that core meaning but has also taken on the nuance of active hostility or opposition to religion or theistic belief, distinct from mere lack of belief (atheism).