'non-religious' originates from the prefix 'non-' meaning 'not' and the word 'religious' from Latin 'religiosus', where 'religio' meant 'reverence or obligation'.

'religiosus' transformed into the Old French word 'religieux', and eventually became the modern English word 'religious'. The prefix 'non-' was added to form 'non-religious'.

Initially, 'religious' meant 'reverence or obligation', but over time, 'non-religious' evolved to mean 'not relating to or believing in any religion'.