John of Patmos describes his opponents in both Smyrna and Philadelphia as “those who say that they are Jews but are not, but are a synagogue of Satan” (Rev 2:9; 3:9). But when the historian of early Christianity tries to give some historical dimension to these opponents, there unravels one of the signature conundrums of ancient labelling: are the opponents Jews? Non-Jews? Which interpretation is simplest, according to the criterion of Ockham's Razor? And what could these terms have meant for John? Most critically, what terms can we ourselves use to designate these parties without resorting to anachronistic definitions of “Jew” or “Christian”?