Protestantism

Protestantism is a major branch of Christianity. It is defined by several core theological principles. One central idea is justification by faith alone. This means salvation is an unmerited gift of divine grace. Another key concept is the priesthood of all believers. This idea suggests that all Christians have a direct relationship with God. They do not need a human mediator or an exclusive priesthood. Most Protestants also follow the principle of Sola Scriptura. This term means the Bible is the sole infallible source of authority. It is considered higher than church tradition.

The movement began during the Protestant Reformation in the 16th century. Reformers wanted to fix perceived errors and abuses in the Catholic Church. A major point of conflict was the sale of indulgences. The Church sold certificates that purported to remit temporal punishment for sins. Martin Luther challenged this practice in 1517. He published his Ninety-five Theses in the Holy Roman Empire. Luther argued that forgiveness cannot be bought or earned. He believed salvation is a gift from God to those with faith.

Different theological ideas led to various branches of Protestantism. Lutheranism grew from Martin Luther's work. It spread through Germany into Denmark–Norway, Sweden, Finland, Livonia, and Iceland. Calvinism was led by reformers like John Calvin, Huldrych Zwingli, and John Knox. These churches spread to Scotland, Switzerland, France, and the Netherlands. In England, King Henry VIII initiated a political separation from the Catholic Church. This led to the start of Anglicanism under Thomas Cranmer. These different traditions are often called denominations.

Protestants hold different views on how to use the Bible. Some follow a strict Sola Scriptura approach. Others follow a concept called prima scriptura. This view holds that Scripture is the primary source of doctrine. However, it allows tradition, experience, and reason to nurture the religion. Methodists and Anglicans use this approach. Some groups, called Christian fundamentalists, read the Bible in a literalist fashion. They view the text as inerrant and infallible. This differs from the historical-critical method used by others.

The concept of the universal priesthood also shaped church life. This doctrine gives the laity the right to read the Bible in their own language. It also allows them to participate in church government. John Calvin viewed this as a way for believers to relate to God. He believed Christ's priesthood is shared with all people. This is different from the idea of an exclusive, hierarchical priesthood. Some scholars note that this can merge different roles within the church into one spiritual entity.

Protestantism is a very large and diverse group today. It is divided into many denominational families. Major groups include Anglicans, Baptists, Calvinists, Lutherans, Methodists, and Moravians. Other groups include Adventists, Pentecostals, Quakers, and Charismatic Christians. There is also a rapid rise in non-denominational or independent churches. These are often called "popular Protestantism" by scholars like Peter L. Berger. These movements are considered some of the most dynamic religious movements in the world.

Estimates of the Protestant population vary by source. In 2004, Hans Hillerbrand estimated the population at 833,457,000. The World Christian Database provided different figures for the early 2026 period. It estimated 637,856,000 Protestants. It also estimated 426,370,000 Independents. Many of these Independents are non-denominational Pentecostals. While they may not self-identify as Protestant, they are included in these broad studies. This shows the massive global scale of these various traditions.