For centuries before the Reformation, Western European Christianity was largely united institutionally under the Roman Catholic Church.
That unity did not mean that everyone agreed about theology or church practice. Medieval Christianity included vigorous debates about theology, authority, worship, monasticism, and reform.
By the late Middle Ages, calls for reform had become increasingly prominent.
Critics objected to corruption among some clergy, the accumulation of wealth and political power within the church, and various religious practices they believed had departed from biblical Christianity.
Earlier reformers anticipated some concerns later associated with Protestantism.
In fourteenth-century England, John Wycliffe criticized aspects of papal authority and emphasized the importance of Scripture. His followers became known as the Lollards.
In Bohemia, Jan Hus advocated reforms influenced partly by Wycliffe. Hus was condemned for heresy and executed in 1415, but his movement survived.
Neither man was a Protestant in the later denominational sense, but both became important predecessors in Protestant accounts of the Reformation.
Martin Luther and the Beginning of the Reformation
The event traditionally associated with the beginning of the Protestant Reformation occurred in 1517.
Martin Luther, an Augustinian monk and professor at the University of Wittenberg, challenged the preaching and sale of indulgences by issuing his famous Ninety-Five Theses.
The controversy quickly expanded beyond indulgences.
Luther increasingly questioned papal authority and argued that Scripture possessed authority above popes and church councils. He also emphasized justification by faith and the grace of God as the basis of salvation.
In 1521, Luther appeared before the Diet of Worms, where he was ordered to recant teachings that had been condemned by church authorities. He refused to withdraw his writings unless convinced by Scripture or sound reasoning.
Luther was subsequently declared an outlaw within the Holy Roman Empire.
His ideas nevertheless spread rapidly, aided considerably by the relatively new technology of the printing press.
The movement surrounding Luther eventually developed into Lutheranism, particularly in Germany and Scandinavia.
The Swiss Reformation
The Reformation developed independently in Switzerland.
Huldrych Zwingli led reforms in Zürich beginning in the 1520s. Like Luther, Zwingli emphasized biblical authority and rejected a number of medieval Catholic practices.
However, Luther and Zwingli disagreed sharply over the Lord’s Supper.
Luther maintained a strong understanding of Christ’s real presence in Communion, while Zwingli emphasized the meal primarily as a memorial.
Their inability to resolve this disagreement demonstrated that Protestantism would not develop as a single unified movement.
A second generation of Swiss reform was led by John Calvin in Geneva.
Calvin became one of the most influential theologians in Protestant history. His Institutes of the Christian Religion provided a systematic presentation of Reformation theology.
The Reformed tradition influenced churches throughout Switzerland, France, the Netherlands, Scotland, England, and eventually North America and other parts of the world.
The Radical Reformation
Some reformers believed Luther and the Swiss Reformers had not gone far enough.
Movements collectively known as the Radical Reformation rejected infant baptism and argued that baptism should follow a personal profession of faith.
These Christians became known as Anabaptists, meaning “rebaptizers,” a label originally applied to them by their opponents.
Many Anabaptists also advocated a stronger separation between church and civil government and emphasized voluntary Christian discipleship.
They were persecuted by both Catholic and Protestant authorities.
Anabaptist traditions eventually contributed to groups such as the Mennonites, Amish, and Hutterites and helped establish ideas that later became important to broader discussions of religious liberty.
The English Reformation
The Reformation in England followed a different course.
Henry VIII initially opposed Luther’s teachings. His conflict with Rome developed primarily from his attempt to have his marriage to Catherine of Aragon annulled.
After Pope Clement VII refused the annulment, a series of parliamentary actions culminated in the Act of Supremacy of 1534, which recognized the English monarch as supreme head of the Church of England.
English Protestantism subsequently developed through a complicated mixture of political and theological change.
Under Edward VI, Protestant reforms accelerated. Under Mary I, England temporarily returned to Roman Catholicism and Protestant leaders were persecuted.
Under Elizabeth I, the Church of England established a more durable Protestant identity while retaining many elements of historic liturgy and episcopal church government.
The resulting Anglican tradition would eventually spread throughout the British Empire and beyond.
The Catholic Reformation
The Protestant Reformation also contributed to significant reforms within Roman Catholicism.
The Catholic response is sometimes called the Counter-Reformation, although historians also use the term Catholic Reformation to emphasize reform movements that were not simply reactions to Protestantism.
The Council of Trent, meeting between 1545 and 1563, clarified Catholic teaching on Scripture and tradition, justification, the sacraments, and other disputed issues while addressing abuses within church life.
New religious movements, particularly the Society of Jesus, or Jesuits, became important forces in Catholic education, missions, and reform.
By the end of the sixteenth century, the major theological divisions between Catholic and Protestant Christianity had become firmly established.
Confessional Protestantism
During the generations following the first Reformers, Protestant churches developed formal statements of faith.
Lutherans produced documents eventually collected in the Book of Concord.
Reformed churches developed confessions such as the Heidelberg Catechism, Belgic Confession, and later the Westminster Confession of Faith.
Anglican doctrine was expressed particularly through the Thirty-Nine Articles.
These documents helped define the theological identities of emerging Protestant traditions.
The period also demonstrated how closely religion and politics remained connected. Religious conflict contributed to wars and political struggles across Europe, including the Thirty Years’ War of 1618–1648.
Puritans, Separatists, and Baptists
Within England, some Protestants believed the Church of England still retained too many practices inherited from Roman Catholicism.
Those seeking further reform became broadly associated with Puritanism.
Some remained within the Church of England and attempted to reform it. Others separated from it entirely.
During the seventeenth century, Baptist churches emerged from this environment. Baptists emphasized believer’s baptism, congregational church life, and, increasingly, religious liberty.
English religious disputes also crossed the Atlantic.
Puritans, Separatists, Anglicans, Quakers, Baptists, and other groups established communities in the North American colonies, helping make Protestantism a major influence on the religious development of what became the United States.
Pietism and the Evangelical Revivals
By the seventeenth and eighteenth centuries, some Protestants worried that Christianity had become overly formal or intellectual.
Pietism, especially within German Lutheranism, emphasized personal conversion, Bible study, holy living, and practical Christian devotion.
Similar concerns helped produce major evangelical revivals in Britain and North America.
The eighteenth-century Great Awakening emphasized personal conversion and the necessity of an active faith.
Preachers such as George Whitefield carried the revival message across denominational boundaries.
At roughly the same time, John Wesley and Charles Wesley led a revival movement within the Church of England emphasizing conversion, disciplined Christian living, and sanctification.
Their movement eventually developed into Methodism.
These revivals helped establish what would later be known as Evangelical Christianity.
Protestantism in the Nineteenth Century
The nineteenth century brought enormous Protestant expansion.
Missionary societies carried Protestant Christianity throughout Africa, Asia, Latin America, and the Pacific.
Protestant churches also became deeply involved in education, publishing, charitable work, and social reform.
The century saw numerous revival movements and the rapid growth of denominations, particularly in the United States.
At the same time, new intellectual challenges emerged.
Historical criticism of the Bible, developments in geology and biology, industrialization, and changing political philosophies generated intense debates within Protestant churches.
Different responses to these developments contributed to theological divisions that continued into the twentieth century.
Fundamentalism and Modernism
During the late nineteenth and early twentieth centuries, many Protestant churches experienced conflicts between theological conservatives and theological liberals or modernists.
Modernist theologians attempted to engage contemporary biblical scholarship, science, and philosophy while reformulating aspects of traditional Christian belief.
Conservative Protestants defended doctrines they considered essential to historic Christianity, including biblical authority, Christ’s divinity, the virgin birth, Christ’s atoning death, and bodily resurrection.
The movement known as Fundamentalism emerged from these controversies, particularly in the United States.
During the mid-twentieth century, a broader movement known as Evangelicalism developed that shared many conservative theological convictions while seeking greater engagement with universities, culture, missions, and public life.
The Rise of Pentecostalism
One of the most significant developments in modern Protestant history was the emergence of Pentecostalism.
Early Pentecostals emphasized the continuing work of the Holy Spirit, including spiritual gifts such as speaking in tongues, prophecy, divine healing, and miracles.
The Azusa Street Revival, beginning in Los Angeles in 1906 under the leadership of William J. Seymour, became an especially influential center of the early movement.
Pentecostalism spread rapidly across racial, national, and denominational boundaries.
Later Charismatic movements brought similar beliefs about spiritual gifts into Anglican, Lutheran, Reformed, Catholic, and other established churches.
Pentecostal and Charismatic Christianity eventually became major forces within global Christianity.
Protestantism Becomes Global
Although Protestantism originated in Europe, it is no longer primarily a European phenomenon.
Centuries of missionary activity, indigenous church movements, revival, migration, and population growth have produced large Protestant communities throughout Africa, Asia, Latin America, Oceania, and the Americas.
Many of the fastest-growing expressions of Protestant Christianity have been Evangelical, Pentecostal, or independent churches.
This global expansion has also changed Protestantism itself.
Christian leaders outside Europe and North America increasingly shape Protestant theology, missions, worship, and church life.
As a result, modern Protestantism cannot adequately be understood simply as a European Reformation movement exported elsewhere. It has become a diverse worldwide family of Christian traditions.
A Tradition of Continuing Reform
Protestant history began with a call for reform, but the Reformation did not produce a final or uniform form of Protestant Christianity.
Lutherans, Reformed Christians, Anglicans, Anabaptists, Baptists, Methodists, Evangelicals, Pentecostals, and many independent churches emerged at different times and under different circumstances.
They continue to disagree about important theological and practical questions.
Yet most remain connected historically to the central concerns that drove the Reformation: the authority of Scripture, the nature of salvation, the person and work of Jesus Christ, and the conviction that the church must continually measure its teaching and practice against the Christian gospel.
Understanding that history helps explain both the remarkable diversity of Protestant Christianity and the theological heritage its many traditions continue to share.