'proselytize' originates from Greek, specifically the word 'prosēlytos,' where 'pros-' meant 'toward' and 'ēlytos' meant 'to come.'

'prosēlytos' transformed into the Latin word 'proselytus,' and eventually became the modern English word 'proselytize' through Old French 'proselyte.'

Initially, it meant 'to convert someone to a religion,' but over time it evolved into its current meaning of 'to convert someone to a belief or cause.'