One of the three major branches of Christianity , originating in the 16th-century Reformation .
The term applies to the beliefs of Christians who do not adhere to Roman Catholicism or Eastern Orthodoxy . A variety of Protestant denominations grew out of the Reformation. The followers of John Calvin and more radical reformers such as Huldrych Zwingli founded Reformed churches in Switzerland, and Calvin's disciple John Knox established a church in Scotland ( Presbyterianism ). Another important branch of Protestantism, represented by the Church of England and Episcopal Church , had its origins in 16th-century England and is now the Protestant denomination closest to Roman Catholicism in theology and worship. The doctrines of the various Protestant denominations vary considerably, but all emphasize the supremacy of the {{link=Bible">Bible in matters of faith and order, justification by grace through faith and not through works, and the priesthood of all believers. In the early 21st century there were nearly 350 million Protestants in the world. See also Adventist , Baptist , Society of Friends , Mennonite , Methodism .