Cryptojew

Crypto-Judaism is the secret adherence to Judaism while publicly professing to be of another faith; practitioners are referred to as "crypto-Jews" (origin from Greek kryptos – κρυπτός, 'hidden').

The term is especially applied historically to Spanish Jews who—outwardly—professed Catholicism, who were also known as Anusim or Marranos. The phenomenon is especially associated with renaissance Spain, following the June 6, 1391, Anti-Jewish pogroms and the expulsion of the Jews in 1492.

Officially, Jews who converted in Spain in the 14th and 15th centuries were known as Cristianos Nuevos (New Christians), but were commonly called conversos. Spain and Portugal passed legislation restricting their rights in the mother countries and colonies; only Christians were allowed to go to the New World. Despite the dangers of the Inquisition, many conversos continued to secretly and discreetly practice Jewish rituals.

After the Alhambra decree of 1492 numerous conversos, also called Xueta (or Chueta) in the Balearic Islands ruled by Spain, publicly professed Roman Catholicism but privately adhered to Judaism, even through the Spanish Inquisition. They are among the most widely known and documented crypto-Jews.

Crypto-Judaism existed also in earlier periods, whenever Jews were forced or pressured to convert to the majority religion by the rulers of places where they resided. Some of the Jewish followers of Sabbatai Zevi (Sabbateans) formally converted to Islam. Later followers of Jacob Frank ("Frankists") formally converted to Christianity, but maintained aspects of practice of their versions of Messianic Judaism.

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Wikipedia