In the 2nd — 4th centuries of the Common Era, Christianity endured periods of intense persecution while working to define its identity and beliefs.
Schisms and Sects
Christianity permanently split twice. The first split occurred between the Byzantine Church (eastern) and the Roman Church (western). The Protestant Reformation further split the Roman or western Church.
Missions and Expansion
From the 5th–13th centuries, Christianity spread dynamically, while the disintegration of the Roman Empire in the West caused churches in the east and west to develop along separate paths.
Exploration and Conquest
From the 15th–19th centuries, Christian missionary activity, often allied with European political expansion, carried Christianity to all parts of the globe.
The 20th century presented Christianity with dizzying political and cultural challenges. A lively and articulate Christianity in former mission fields and dissatisfaction among American evangelicals produced new movements.