The Timeline and History of Christianity

Preface: When Christianity began, there were no denominations. Christ established one Church, entrusted it to His apostles, and commanded them to teach the faith they had received from Him. Jesus prayed that His followers would “all be one” (John 17:21), and St. Paul described the Church as “one body” with “one Lord, one faith, one baptism” (Ephesians 4:4–5). From the beginning, Christians belonged to one united Church. That Church spread throughout the Roman Empire and beyond, eventually developing distinct cultural expressions in the Greek-speaking East and the Latin-speaking West, but these differences did not originally imply that they were separate churches.

The early Church faced disagreements and false teachings almost immediately, but it dealt with them through the authority Christ had given His apostles and their successors—without schism. Bishops from across the Christian world gathered in councils to defend the apostolic faith, and the first seven Ecumenical Councils clarified foundational Christian beliefs about the Trinity, Christ, the Holy Spirit, and the Incarnation. The Nicene-Constantinopolitan Creed, which Orthodox Christians still confess today, came from this shared life of the ancient Church. For over a thousand years, Christians in both East and West shared the same essential faith, sacraments, bishops, Eucharistic worship, and apostolic tradition.

Over time, serious divisions developed between the Christian East and West, particularly over theology and ecclesiastical authority. One of the most significant disputes concerned the Filioque, meaning “and the Son” in Latin. The original Nicene-Constantinopolitan Creed confessed that the Holy Spirit “proceeds from the Father.” The Western Church later added the words “and the Son” to the Creed, despite the Creed having been established by an Ecumenical Council and despite the fact that no Ecumenical Council had authorized the alteration. The West also increasingly developed a broader understanding of the authority of the Bishop of Rome, including claims of universal papal jurisdiction that differed from the Church’s earlier conciliar structure. These changes represented a significant departure from the theological and ecclesiastical tradition received from the apostles and preserved by the early Church. Alongside growing political and cultural tensions between East and West, these theological and ecclesiastical differences eventually led to the separation of communion between the Western and Eastern churches.

For the next several centuries, Western Christianity remained centered around the Roman Catholic Church, although there were significant internal disputes and calls for reform. Eventually, another major division occurred in the West. In 1517, Martin Luther, a German monk and university professor, publicly challenged certain practices of the Catholic Church, particularly abuses surrounding indulgences. Luther initially sought reform rather than the creation of an entirely separate Christianity, but his disagreements with Rome expanded into fundamental disputes concerning the authority of the Pope, salvation, the sacraments, and the role of Church Tradition. His movement became one of the major starting points of the Protestant Reformation.

From there, Western Christianity experienced further fragmentation. Luther’s followers became Lutherans, while other reformers such as John Calvin and Huldrych Zwingli developed the Reformed tradition. Anglicanism developed through the English Reformation, and later movements gave rise to Baptists, Presbyterians, Methodists, Pentecostals, and countless other Protestant denominations. These groups did not all originate directly with Luther, but they emerged from the broader Protestant movement and the ongoing divisions within Western Christianity.

The Eastern Orthodox understanding of this history is therefore fundamentally about continuity. Christianity began as one apostolic Church. The East and West were originally united. The West eventually separated from the East through a long process of theological, ecclesiastical, cultural, and political division, with the Filioque and the question of papal authority being among the major theological issues. The East remained committed to the faith expressed through the ancient Church, the Ecumenical Councils, the apostolic succession of its bishops, the sacraments, and the liturgical worship it had inherited. Centuries later, the Western Church experienced another major rupture through the Protestant Reformation, resulting in the enormous denominational landscape familiar to Christians today.

This is why the Orthodox Church does not understand itself as simply one denomination among many, but as the continuation of the ancient Church that existed before the major divisions of Christianity. This claim should not be accepted merely because Orthodoxy says so; it should be examined through Scripture and history. Before deciding which doctrines or practices are correct, it is important to understand where they originated, when they emerged, and whether they were part of the early Church’s faith or developed centuries later. Church history provides the context needed to understand how Christianity was originally believed and practiced and to distinguish the apostolic Church from the later branches that developed from it. The fundamental question, then, is not simply, “Which denomination do I personally prefer?” but rather: What did the Church of the apostles believe, how did it worship, how was its authority preserved, and which Church today has maintained that same faith and life? For the Orthodox Christian, the answer is the Orthodox Church: the Church that has preserved the apostolic faith, worship, sacraments, and succession handed down through the ancient Church.