'antidemonist' originates from Modern English, specifically the prefix 'anti-' (from Greek 'anti-' meaning 'against') combined with 'demon' (from Greek 'daimon' meaning 'spirit') and the agent suffix '-ist' meaning 'one who' (forming 'one who is against belief in demons').

'antidemonist' was formed in English by compounding the productive elements 'anti-' + 'demon' + '-ist'; it is a relatively modern, transparent formation rather than a word with a long separate historical development.

Initially formed to mean 'one opposed to belief in demons'; this basic sense has remained consistent, functioning as a descriptive label (often critical or academic) rather than undergoing major semantic shift.