When Christianity first began, it wasn’t immediately clear that it was a “new religion.” The earliest followers of Jesus were Jewish, and outsiders often saw them as just another Jewish sect. In fact, the very first time people were called “Christians” (in Acts 11:26) it was more of a nickname than an official title. Some even called them “Nazarenes,” linking them back to Jesus of Nazareth.
But between the time of the Apostles and the fourth century, Christianity gradually came to be seen as something distinct from Judaism. That shift didn’t happen overnight—it developed through persecution, legal distinctions, and the defining of Christian beliefs at events like the Council of Nicaea.
Persecution
One of the biggest forces that pushed Christianity to stand apart was persecution. At first, much of this came from fellow Jews. The book of Acts records how Stephen, the first Christian martyr, was killed because of disputes about his identity as a “half-Jew.” The apostle Paul even admitted that, before his conversion, he tried to destroy the early church out of zeal for Judaism (Galatians 1:13).
Soon, however, persecution came from Rome itself. Roman historians record several moments where Christians were singled out:
- Emperor Claudius expelled Jews from Rome because of disturbances involving “Chrestus” (likely a misspelling of Christus, meaning Christ).
- Emperor Nero blamed Christians for the great fire of Rome in 64 AD and put many to death.
- In the city of Lyon about a century later, Christians were still being tortured and executed.
Over time, these attacks grew from the actions of individual rulers to full-scale government policy. By the reign of Diocletian in the late third century, persecution was no longer local but empire-wide, with the stated goal of wiping Christianity out entirely.
Legal Distinctions
Law also played a major role in separating Christians from Jews. After the Jewish Temple was destroyed in 70 AD, Rome created a special tax on Jews called the fiscus Iudaicus (“Jewish tax”). At that point, Christians argued they should be exempt—because they were not Jews but a different community.
This was an important step in Rome beginning to treat Christianity as something separate. By the early fourth century, this divide widened dramatically. In 313 AD, emperors Constantine and Licinius issued the Edict of Milan, which granted freedom of worship to Christians. Instead of being hunted down, they now had legal protection. This set the stage for Christianity to move from the margins of society to the very center of the Roman Empire.
Defining Beliefs
Even with legal recognition, Christianity still needed to define itself theologically. In 325 AD, the first Council of Nicaea was convened. This meeting of bishops from across the empire was designed to settle disputes about who Jesus really was.
The outcome was groundbreaking: Christianity formally declared that Jesus was not just a prophet or a moral teacher, but fully divine and worthy of worship. This emphasis on Christ as the Son of God gave Christianity a clear doctrinal identity, different from both Judaism and pagan religions.
It took three centuries of persecution, legal battles, and theological debate for Christianity to emerge as a distinct religion. What began as a small Jewish movement became a faith with its own laws, freedoms, and core beliefs, ready to shape the future of Europe and beyond.
By the late fourth and fifth centuries, Christianity’s identity would be refined even further—through the establishment of the biblical canon, the creation of church leadership structures, and the organization of worship practices. But those first three centuries laid the foundation for what Christianity would become.
