Isopsephy left a visible trail through the Hellenistic and Roman worlds, appearing in graffiti scratched into the walls of Pompeii, in riddling epigrams collected in the Greek Anthology, and in the composition of magical amulets, where a divine name's numeric total might be inscribed alongside or instead of the name itself, on the reasoning that the number carried the name's power in condensed form. The technique was not confined to any one religious community: pagan, Jewish and Christian writers working in Greek all made use of it, each applying it to the names and phrases that mattered within their own tradition.
Because the method is entirely mechanical once the numeral table is known, isopsephy invites both genuine historical use and modern amateur reconstruction that goes well beyond what any ancient source claims, and readers should distinguish the two carefully: that isopsephy existed and was practised is well attested by inscriptions and literary examples; particular modern claims about what specific ancient totals were meant to signify are frequently later interpretation layered onto an old technique rather than a preserved ancient explanation.
Sources The Oxford Classical Dictionary, 4th editionSimon Hornblower, Antony Spawforth and Esther Eidinow (eds.) with The Greek Magical Papyri in Translation, Including the Demotic SpellsHans Dieter Betz, editor