While the word, Christianity might conjure up images of monumental cathedrals and powerful bishops, the religion was not always so powerful. In fact, Christians were persecuted throughout the Roman Empire for centuries. Some, like Emperor Nero, famously blamed Christians for whatever went wrong, including a fire that burned much of Rome. As a result, Christians remained secretive, sometimes going as far as to meet and worship in underground catacombs. However, this persecution couldn't stop the spread of Christianity!
Many people were tired of Roman state rituals that seemed empty and were attracted to the idea of social equality, justice, and the promise of an afterlife that Christianity offered. Beginning in the Middle East, Christianity began its spread north and west into Europe, carried by merchants, missionaries, and soldiers. Of course, the Roman imperial government couldn't ignore the fact that, despite the persecutions, Christianity was growing stronger.
As a result, in 313, the Edict of Milan was passed, which guaranteed freedom of religion throughout the Roman Empire, ending the persecution of Christians. Such a measure was partially designed to help Christians have more faith in the Roman Empire, which was growing weak. Ultimately, however, this wouldn't be enough to restore people's trust in the Western Roman Empire, which fell in the year 476. Still, Christianity was here to stay