History, and being what was called a Crypto-Jew

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 and Portuguese Jews who outwardly professed Catholicism, also known as Conversos, Marranos, or the Anusim. The phenomenon is especially associated with medieval Spain, following the Massacre of 1391 and the expulsion of the Jews in 1492. After 1492 in Spain and 1497 in Portugal, officially they no longer existed. The Spanish Inquisition and the Portuguese Inquisition were established to monitor converted Jews and their descendants for their continued adherence to Christian faith and practice, with severe penalties for those convicted of secretly continuing to practice Judaism. Information about secretly observant Jews largely survives in Inquisition cases against individuals.

Officially, Jews who converted in Spain during the 14th and 15th centuries were known as Cristianos Nuevos (New Christians), but were commonly called conversos (converts to Christianity). Spain and Portugal issued edicts restricting their rights in the mother countries of Spain and Portugal and Spanish and Portuguese overseas territories in the Americas.

Although only Cristianos Viejos (Old Christians) who could prove limpieza de sangre ("cleanliness or purity of blood") descended from Christian Iberian European ancestry only, without "tainting" of any Jewish ancestry or Muslim Berber/Arab ancestry, were allowed to officially migrate to the New World Spanish possessions, many Christian conversos with Jewish antecedents went to the Spanish possessions, using forged limpieza de sangre documents, or they entered the Spanish possessions via Portuguese Brazil, particularly 1580-1640 when Spain and Portugal were ruled by the same monarch. The entry requirements to the Portuguese colony of Brazil were more lax and also less rigorously enforced.

Despite the dangers of the Spanish Inquisition in Iberia and the Inquisitions established in Mexico City; Lima, Peru; and Cartagena de Indias in what is now Colombia, many conversos continued to secretly and discreetly practice Jewish rituals in the home, such as the Festival of Santa Esterica, a disguised version of Purim to celebrate the Jewish Queen Esther with a fictional “Catholic” Saint Esterica.

After the Alhambra decree of March 1492, which mandated conversion to Christianity or exile for Jews, 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 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 and were known as Dönmeh. Later followers of Jacob Frank (Frankists) formally converted to Christianity but maintained aspects of practice of their versions of Judaism.

The "Belmonte Jews" of Portugal, dating from the 12th century, maintained strong secret traditions for centuries. A whole community survived in secrecy by maintaining a tradition of endogamous marriage and hiding all external signs of their faith. They and their practices were discovered only in the 20th century. Their rich Sephardic tradition of crypto-Judaism is unique. Some now profess Orthodox Judaism, although many still retain their centuries-old traditions.

Notable crypto-Jews

• Antonio Fernandez Carvajal was a Portuguese merchant in London; "like other Marranos in London, Carvajal prayed at the Catholic chapel of the Spanish ambassador, while simultaneously playing a leading role in the secret Jewish community, which met at the clandestine synagogue at Creechurch Lane."
• Isaac Cardoso was a Jewish physician, philosopher, and polemic writer, who was born in Portugal but ultimately settled in Italy. For a time he went by the name Fernando to evade the Inquisition. After finding safe haven in Verona he openly embraced Judaism, becoming a leading scholar in Italy.
• Benjamin Melendez was a Nuyorican activist, musician and gang leader. He is best known for brokering the New York City gang truce in 1971, while President of the South Bronx gang (and musical group) the Ghetto Brothers.