A Nicodemite ( /ˌnɪkəˈdiːmaɪt/ )  is a person suspected of publicly misrepresenting their religious faith to conceal their true beliefs.   The term is sometimes defined as referring to a Protestant Christian who lived in a Roman Catholic country and escaped persecution by concealing their Protestantism.  
The word is normally a term of disparagement. Introduced into 16th-century religious discourse, it persisted in use into the 18th century and beyond. Originally employed mostly by Protestants, it was usually applied to persons of publicly conservative religious position and practice who were thought to be secretly humanistic or reformed.
Friedrich Heer in his book The Medieval World (1961; English translation published in 1962) refers to the 12th-century circle at Chartres as past masters of nicodemism, which he describes as "dangerous thoughts, dangerous allusions to topical ecclesiastical and political affairs, and above all to ideas hard or impossible to reconcile with the dogma of the Church or the maxims of the prevailing theology". 
In England during the 17th and 18th centuries the term was often applied to those suspected of secret Socinian, Arianist, or proto-Deist beliefs. 
The term was apparently introduced by John Calvin (1509–1564) in 1544 in his Excuse à messieurs les Nicodemites.  Since the French monarchy had increased its prosecution of heresy with the Edict of Fontainebleau (1540), it had become increasingly dangerous to profess dissident belief publicly, and refuge was being sought in emulating Nicodemus.
In the Gospel of John (John 3, John 3:1-2) there appears the character Nicodemus, a Pharisee and member of the Sanhedrin. Although outwardly remaining a pious Jew, he comes to Jesus secretly by night to receive instruction. Although he was eventually made a saint, his dual allegiance was somewhat suspect.
There was a man of the Pharisees, named Nicodemus, a ruler of the Jews: The same came to Jesus by night, and said unto him, Rabbi, we know that thou art a teacher come from God: for no man can do these miracles that thou doest, except God be with him.
Recusancy was the state of those who remained loyal to the Catholic Church and refused to attend Church of England services after the English Reformation.
The Reformation was a major movement within Western Christianity in 16th-century Europe that posed a religious and political challenge to the Catholic Church and in particular to papal authority, arising from what were perceived to be errors, abuses, and discrepancies by the Catholic Church. The Reformation was the start of Protestantism and the split of the Western Church into Protestantism and what is now the Roman Catholic Church. It is also considered to be one of the events that signified the end of the Middle Ages and the beginning of the early modern period in Europe.
Peter Martyr Vermigli was an Italian-born Reformed theologian. His early work as a reformer in Catholic Italy and his decision to flee for Protestant northern Europe influenced many other Italians to convert and flee as well. In England, he influenced the Edwardian Reformation, including the Eucharistic service of the 1552 Book of Common Prayer. He was considered an authority on the Eucharist among the Reformed churches, and engaged in controversies on the subject by writing treatises. Vermigli's Loci Communes, a compilation of excerpts from his biblical commentaries organised by the topics of systematic theology, became a standard Reformed theological textbook.
Socinianism is a Nontrinitarian Christian belief system developed and co-founded during the Protestant Reformation by the Italian Renaissance humanists and theologians Lelio Sozzini and Fausto Sozzini, uncle and nephew, respectively.
Nicodemus was a Pharisee and a member of the Sanhedrin mentioned in three places in the Gospel of John:
Cuius regio, eius religio is a Latin phrase which literally means "whose realm, their religion" – meaning that the religion of the ruler was to dictate the religion of those ruled. This legal principle marked a major development in the collective freedom of religion within Western civilization. Before tolerance of individual religious divergences became accepted, most statesmen and political theorists took it for granted that religious diversity weakened a state – and particularly weakened ecclesiastically-transmitted control and monitoring in a state. The principle of "cuius regio" was a compromise in the conflict between this paradigm of statecraft and the emerging trend toward religious pluralism developing throughout the German-speaking lands of the Holy Roman Empire. It permitted assortative migration of adherents to just two theocracies, Roman Catholic and Lutheran, eliding other confessions.
The Polish Brethren were members of the Minor Reformed Church of Poland, a Nontrinitarian Protestant church that existed in Poland from 1565 to 1658. By those on the outside, they were called "Arians" or "Socinians", but themselves preferred simply to be called "Brethren" or "Christians", and, after their expulsion from Poland, "Unitarians".
Crypto-Calvinism is a pejorative term describing a segment of those members of the Lutheran Church in Germany who were accused of secretly subscribing to Calvinist doctrine of the Eucharist in the decades immediately after the death of Martin Luther in 1546. It denotes what was seen as a hidden Calvinist belief, i.e., the doctrines of John Calvin, by members of the Lutheran Church. The term crypto-Calvinist in Lutheranism was preceded by terms Zwinglian and Sacramentarian. Also, Jansenism has been accused of crypto-Calvinism by Roman Catholics.
The Elizabethan Religious Settlement is the name given to the religious and political arrangements made for England during the reign of Elizabeth I (1558–1603). Implemented between 1559 and 1563, the settlement is considered the end of the English Reformation, permanently shaping the theology and liturgy of the Church of England and laying the foundations of Anglicanism's unique identity.
Crypto-Christianity is the secret practice of Christianity, usually while attempting to camouflage it as another faith or observing the rituals of another religion publicly. In places and time periods where Christians were persecuted or Christianity was outlawed, instances of crypto-Christianity have surfaced.
Protestantism originated from the Protestant Reformation of the 16th century. The term Protestant comes from the Protestation at Speyer in 1529, where the nobility protested against enforcement of the Edict of Worms which subjected advocates of Lutheranism to forfeit of all their property. However, the theological underpinnings go back much further, as Protestant theologians of the time cited both Church Fathers and the Apostles to justify their choices and formulations. The earliest origin of Protestantism is controversial; with some Protestants today claiming origin back to people in the early church deemed heretical such as Jovinian and Vigilantius.
In Christian eschatology, historicism is a method of interpretation of biblical prophecies which associates symbols with historical persons, nations or events. The main primary texts of interest to Christian historicists include apocalyptic literature, such as the Book of Daniel and the Book of Revelation. It sees the prophecies of Daniel as being fulfilled throughout history, extending from the past through the present to the future. It is sometimes called the continuous historical view. Commentators have also applied historicist methods to ancient Jewish history, to the Roman Empire, to Islam, to the Papacy, to the Modern era, and to the end time.
Isaac Newton was considered an insightful and erudite theologian by his Protestant contemporaries. He wrote many works that would now be classified as occult studies, and he wrote religious tracts that dealt with the literal interpretation of the Bible. He kept his heretical beliefs private.
The Deposition is a marble sculpture by the Italian High Renaissance master Michelangelo. The sculpture, on which Michelangelo worked between 1547 and 1555, depicts four figures: the dead body of Jesus Christ, newly taken down from the Cross, Nicodemus, Mary Magdalene and the Virgin Mary. The sculpture is housed in the Museo dell'Opera del Duomo in Florence and is therefore also known as the Florentine Pietà.
Waiting for Snow in Havana: Confessions of a Cuban Boy is a 2003 book by Carlos Eire and winner of the National Book Award for Nonfiction. The book is autobiographical, about the author's experiences as part of Operation Peter Pan.
The following outline is provided as an overview of and topical guide to Christianity:
Protestantism is a branch of Christianity that follows the theological tenets of the Protestant Reformation, a movement that began seeking to reform the Catholic Church from within in the 16th century against errors, abuses, and discrepancies.
The term Protestant ecclesiology refers to the spectrum of teachings held by the Protestant Reformers concerning the nature and mystery of the invisible church that is known in Protestantism as the Christian Church.
Church music during the Reformation developed during the Protestant Reformation in two schools of thought, the regulative and normative principles of worship, based on reformers John Calvin and Martin Luther. They derived their concepts in response to the Catholic church music, which they found distracting and too ornate. Both principles also pursued use of the native tongue, either alongside or in place of liturgical Latin.
Catholic–Protestant relations refers to the social, political and theological relations and dialogue between the Catholics and Protestants.
[...] a secret follower or adherent[;] specifically : a 16th century Protestant Christian who lived in a Roman Catholic country and escaped persecution by concealing his or her Protestantism
The term Nicodemite, derived from Nicodemus, who visited Jesus by night, generally denotes a secret or timid adherent. J. Calvin applied it to those converts to Protestantism in Catholic France who outwardly continued RC practices. In modern times Nicodemism covers all forms of religious simulation.