'anti-Christianism' originates from Greek, specifically the prefix 'anti-' (meaning 'against'), combined with Late Latin/Old French-derived 'Christianus' (from which 'Christian' is formed, meaning 'a follower of Christ'), and the English suffix '-ism' that forms nouns describing doctrines or systems.

'anti-Christianism' was formed in English by combining 'anti-' + 'Christianism' (itself from 'Christian' + '-ism'); the compound arose to denote an ideology or attitude opposed to Christianity and entered modern usage in contexts discussing religious or political hostility.

Initially it often referred to opposition to particular Christian doctrines or institutions; over time it broadened to denote more general hostility, prejudice, or systematic opposition toward Christianity and Christians.