'nonbeliever' originates from the prefix 'non-' meaning 'not' and the word 'believer', which comes from Old English 'belȳfan', meaning 'to have faith'.

'belȳfan' transformed into the Middle English word 'bileven', and eventually became the modern English word 'believe'.

Initially, it meant 'to have faith', but over time it evolved into its current meaning of 'one who does not have faith in a particular belief'.