The Puritans were members of a group of radical Protestants which developed in England after the Reformation.
The word Puritan is now applied unevenly to a number of Protestant churches from the late sixteenth century to the early eighteenth century. However, Puritans did not, by and large, use the term for themselves, and the word was always a descriptor of a type of religious innovation, rather than a particular church. The closest analogy in the present day to the meaning of "Puritan" in the 17th century would be "fundamentalist": Puritanism was a movement rather than a denomination.
That said, the single theological movement most consistently self-described by the term "Puritan" was Calvinist and became the Presbyterian Church. The term was used by the group itself mainly in the sixteenth century. By the middle of the seventeenth century the group had become so divided that "Puritan" was most often used by opponents and detractors of the group, rather than by the practitioners themselves. The practitioners knew themselves as members of particular churches or movements, and not by the simple and nebulous term "Puritan."
Puritanism seems to have arisen out of discontent with the Elizabethan Religious Settlement, which was felt by the more radical Protestants to be giving in to "Popery" (i.e., the Catholic Church). While Protestant movements in Europe were being driven by issues of theology and had broken radically with Catholic models of church organization, the English Reformation had brought the church under control of the monarchy while leaving many of its practices intact; in the eyes of the Puritans, this had made doctrine unacceptably subservient to politics. Persecuted under Mary I of England ("Bloody Mary"), Protestants like Thomas Cartwright, Walter Travers and Andrew Melville had gone into exile as Puritans in Europe, where they came into close contact with the radical reformers in Calvinist Geneva and Lutheran Germany. These contacts shaped their position towards Elizabeth's religious via media (middle way).
Although all influenced by Calvinism, Puritans were not united on every issue of doctrine. This is an outgrowth of the origins of the movement, which went through several phases. They shared a belief that all existing churches had become corrupted by practice, by contact with pagan civilizations (particularly Rome), by the impositions of kings and popes. They all argued for a restructuring and "purifying" of church practice through biblical supremacy, and they shared, to one degree or another, a belief in the priesthood of all believers. However, in church polity (organization of church power), they differed.
At the outset, Puritans were simply the informed, committed, and relatively radical Protestants. As a group, they wanted the Church of England to resemble more closely the Protestant churches of Europe, especially Geneva. The Puritans objected to ornaments and ritual in the churches as idolatrous (vestments, surplices, organs, genuflection), which they castigated as "popish pomp and rags." They also objected to ecclesiastical courts. They refused to endorse completely all of the ritual directions and formulas of the Book of Common Prayer; the imposition of its liturgical order by legal force and inspection sharpened Puritanism into a definite opposition movement.
By the 1570s, Puritans were arguing for a Presbyterian model or a Congregationalist model, but all were outspoken in their criticism of the structure and liturgy that the monarchy required. Attempts by the bishops of the Church of England to enforce uniformity of usage in the Book of Common Prayer turned the episcopal hierarchy into a specific target of their grievances. Tracts such as the Martin Marprelate series lampooned the government and the church hierarchs.
The issue of church hierarchy was difficult, and Elizabeth sponsored Richard Hooker to write Of the Laws of Ecclesiastical Polity to counter presbyterian arguments. Hooker writes in direct refutation of the "brothers of the Geneva Church," and he outlines a via media for the English church that, rather than being the absence of doctrine, is a set of specifically ordained rules. His thinking on the matter became the backbone of the Anglican church and would later be put to use by Archbishop William Laud.
These radicals were looked down on by the dominant Anglo-Catholic faction in the Church of England and were given the name "Puritan", in mockery of the radicals' apparent obsession with "purifying" the Church.
Contemporarily with the English Reformation, the Church of Scotland had been created on a Calvinist Presbyterian model, which many Puritans hoped to extend to England. When James VI of Scotland became James I of England, he appointed several known Puritans to powerful positions within the Church of England, and he checked the rise of William Laud. Nevertheless, he was no Puritan, and he regarded Puritans with great suspicion. Since he believed in royal control of the Church he saw Puritanism as a potentially dangerous movement; he authorized the King James Bible partly to reinforce Anglican orthodoxy against the Geneva Bible, which had become popular among Puritans. Luther had insisted on a vulgar Bible for each language, as well as for vernacular church services. Since all Puritan sects were, essentially, believers in biblical supremacy, the presence of an English language Bible was paramount. The Geneva Bible, however, had peculiarly anti-royalist translations and interpolated revolutionary notes.
Each new round of political disappointments during this period faced each individual Puritan and the Puritan congregations with a new crisis. The question was whether they were to continue in outward conformity with a distasteful religious regime, or did they take the separatist and illegal step of withdrawal from the state church? Each fresh controversy led to a new round of schisms, and as such the groundwork was set for the eventual heirs of Puritanism, from the "low-church" Protestant and Evangelical wing of the Church of England, to the various dissenting sects.
During the reign of Charles I, a committed High Churchman, relations soured and it is a common belief among historians that religious tensions created by the dominance of the Laudian faction during the Personal Rule were a major factor in the outbreak of the English Civil War. Puritans certainly agitated against the king, and reform of the religion was a rallying cry for the Parliamentary forces. However, Puritanism by this point had become not merely a religion, but a cultural entity.
By this time, Puritans were more often referred to as Dissenters. Dissenters were barred from any profession that required official religious conformity, and so Puritans had been instrumental in a number of new industries. First, export/import was dominated by Puritans. Second, Puritans were eager colonials. With the flourishing of the trans-Atlantic trade with America, Puritans in England were growing quite wealthy. Similarly, the artisan classes had become increasingly Puritan, thanks to the Puritan emphasis on preaching and evangelizing. Therefore, the economic issues of the Civil War (tax levies, liberalization of royal charters), the political issues of the Civil War (purchasing of peerages, increasing disconnect between the House of Lords and the people, rebellion over the attempt to introduce a Divine right of kings to Charles I), and the religious tensions were all bound together into a general issue of Church of England Cavaliers and Puritan Roundheads.
Puritan factions played a key role in the Parliamentarian victory and became a majority in Parliament, while Puritan military leader Oliver Cromwell became head of the English Commonwealth. In the Commonwealth period, the Church of England was removed from Royal control and reorganized to grant greater authority to local congregations, most of which developed in a Puritan and semi-Calvinist direction. There was never an official Puritan denomination; the Commonwealth government tolerated a somewhat broader debate on doctrinal issues than had previously been possible, and considerable theological and political conflict between Puritan factions continued throughout this period. The label "Puritan" fell out of use when their movement became the status quo; it was replaced by the broader term Nonconformist, which was used after the Restoration to refer to all Protestant denominations outside of the official Church.
The influence of the Puritan movement persisted in England as the Evangelical faction of the Church of England, sometimes called "Low Anglican", while in the United States the Puritan settlement of New England was a major influence on American Protestantism.
The Puritans were one branch of dissenters who decided that the Church of England was beyond reform. Escaping persecution from church leadership and the King, they came to America. Most of the Puritans settled in the New England area. As they immigrated and formed individual colonies, their numbers rose from 17,800 in 1640 to 106,000 in 1700. 
Numerous sects split from the Puritan mainstream during the Commonwealth, including the Religious Society of Friends, which could be seen as a radical outgrowth of Puritanism in much the same way that Puritanism was a radical outgrowth of the Reformation. The largest denominational group to emerge from the Puritan experience is the group of Presbyterian denominations, historically Calvinist, and practicing a church policy that rejects episcopacy.
The modern Congregational Church (recently merged with the United Church of Christ) is the direct descendant of New England Puritan congregations, although in the early 19th century a few of these old congregations adopted Unitarianism.
The central tenet of Puritanism was God's supreme authority over human affairs, particularly in the church, and especially as expressed in the Bible. They believed, for example, that the worship of the church ought to be strictly regulated by what is clearly commanded in Scripture. Where their opponents defended many worship practices based on tradition alone, the Puritans considered these practices to be idolatry, regardless of their antiquity or how widespread they were among Christians. Thus, Puritan reforms were typified by a minimum of ritual and decoration, and an unambiguous emphasis on preaching.
Besides the worship and government of the church, the Puritans also emphasized that the individual should be reformed by the grace of God. Each person, upon whom God shows mercy, should have a sense of his own unworthiness and a confidence that the forgiveness which is in Christ has been particularly applied to him; so that out of gratitude, a humble and obedient life would arise.
Other important beliefs included:
- Personal morality
- Education and enlightenment for the masses
- Simple clothes for priests
- Simple ceremonies in Church
- Simple decorations (if any) in Churches
- No "superstition" (e.g.: rejection of transubstantiation)
- Abolition of Church Hierarchy
- Opposition to the Monarch being head of the Church
Most groups also believed the Divine Right of Kings was heresy; this became more pronounced during the reign of Charles I.
Banned in their New England colonies;
- Religious music
- Erotic poetry.
Drama and erotic poetry was believed to lead to immorality. Music in worship was not conducive to listening to God. Knowledge of Greek and Latin was important to them. Diversions included Bible discussions and reading the great Greek classics including Cicero, Virgil, and Ovid. They were incouraged to write their own poetry of religious nature.
In modern usage, "Puritan" is often used as an informal pejorative term for someone who has strict views on sexual morality, disapproves of recreation, and wishes to impose these beliefs on others. None of these qualities were unique to Puritanism or universally characteristic of Puritans, whose moral views and ascetic tendencies were no more extreme than many other Protestant reformers of their time, and who were relatively tolerant of other faiths—at least in England; the popular image is slightly more accurate as a description of Puritans in colonial America, whose social experiment took the form of a Calvinist theocracy.
In the United States, "Puritan" is the only acceptable spelling. Through the twentieth century, British English had "Puritain" as an acceptable alternative spelling. During the seventeenth and eighteenth century in England, the word was spelled both with and without the second /i/. The "Puritain" spelling was more common in the sixteenth century. The word derives from "purity," in English, and the third syllable formation can be justifiably spelled -ian or -an, depending upon which language one derives "dweller"/"practitioner" from
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