Protestantism is the second largest form of Christianity with collectively between 800 million and more than 900 million adherents worldwide or nearly 40% of all Christians. It originated with the 16th century Reformation, a movement against what its followers perceived to be errors in the Roman Catholic Church. Protestants reject the Roman Catholic doctrine of papal supremacy and sacraments, but disagree among themselves regarding the real presence of Christ in the Eucharist. They emphasize the priesthood of all believers, justification by faith alone (sola fide) rather than by good works, and the highest authority of the Bible alone (rather than with sacred tradition) in faith and morals (sola scriptura). The "five solae" summarize basic theological differences in opposition to the Roman Catholic Church.
Protestantism is popularly considered to have begun in Germany in 1517 when Martin Luther published his Ninety-five Theses as a reaction against abuses in the sale of indulgences by the Roman Catholic Church, which purported to offer remission of sin to their purchasers. Although there were earlier breaks and attempts to reform the Roman Catholic Church—notably by Peter Waldo, John Wycliffe, and Jan Hus—only Luther succeeded in sparking a wider, lasting, and modern movement. In the 16th century, Lutheranism spread from Germany into Denmark, Norway, Sweden, Finland, Latvia, Estonia, and Iceland. Reformed (or Calvinist) denominations spread in Germany, Hungary, the Netherlands, Scotland, Switzerland and France by reformers such as John Calvin, Huldrych Zwingli, and John Knox. The political separation of the Church of England from the pope under King Henry VIII began Anglicanism, bringing England and Wales into this broad Reformation movement.
Although the Reformation was a religious movement, it also had a strong impact on all other aspects of life: marriage and family, education, the humanities and sciences, the political and social order, the economy, and the arts. Protestant churches reject the idea of a celibate priesthood and thus allow their clergy to marry. Many of their families contributed to the development of intellectual elites in their countries. Since about 1950, women have entered the ministry, and some have assumed leading positions (e.g. bishops), in most Protestant churches.
As the Reformers wanted all members of the church to be able to read the Bible, education on all levels got a strong boost. By the middle of the eighteenth century, the literacy rate in England was about 60 per cent, in Scotland 65 per cent, and in Sweden eight of ten men and women were able to read and to write. Colleges and universities were founded. For example, the Puritans who established Massachusetts Bay Colony in 1628 founded Harvard Collegeonly eight years later. About a dozen other colleges followed in the 18th century, including Yale (1701). Pennsylvania also became a centre of learning.
Protestantism is diverse, being more divided theologically and ecclesiastically than either the Roman Catholic Church, the Eastern Orthodox Church, or Oriental Orthodoxy. Without structural unity or central human authority, Protestants developed the concept of an invisible church, in contrast to the Roman Catholic view of the Catholic Church as the visible one true Church founded by Jesus Christ. Some denominations do have a worldwide scope and distribution of membership, while others are confined to a single country. A majority of Protestants are members of a handful of Protestant denominational families: Adventists, Anabaptists, Anglicans, Baptists, Reformed, Lutherans, Methodists, and Pentecostals. Nondenominational, evangelical, charismatic, independent and other churches are on the rise, and constitute a significant part of Protestant Christianity. Proponents of the branch theory consider Protestantism one of the three major divisions of Christendom, together with the Roman Catholic Church and Orthodoxy (both Eastern and Oriental).
There are more than 900 million Protestants worldwide. In 2010, a total of more than 800 million included 300 million in Sub-Saharan Africa, 260 million in the Americas, 140 million in Asia-Pacific region, 100 million in Europe and 2 million in Middle East-North Africa. Protestants account for nearly forty percent of Christians worldwide and more than one tenth of the total human population.
In European countries which were most profoundly influenced by the Reformation, Protestantism still remains the most practiced religion. These include the Nordic countries and the United Kingdom. In other historical Protestant strongholds such as Germany, the Netherlands, Switzerland, Latvia, Estonia and Hungary, it remains one of the most popular religions.