'anti-Christianity' originates from Modern English, formed from the prefix 'anti-' (from Greek 'anti-' meaning 'against') + 'Christianity' (from Latin/Greek roots referring to followers of Christ).

'Christianity' developed from Latin 'Christianitas' and Old English forms such as 'Cristendom'; 'Christian-' ultimately comes from Greek 'Christos' meaning 'anointed' (referring to Christ). The prefix 'anti-' comes from Greek 'anti' meaning 'against'. These elements combined in Modern English to form 'anti-Christianity'.

Initially, 'anti-' simply indicated 'against' and 'Christianity' designated the Christian religion; together, the combined term has come to denote organized or ideological opposition to Christianity, including social, political, or cultural dimensions.