Christianity provided its followers with nonmaterial benefits that the traditional Roman culture and religions did not. Christianity also was open in sharing its beliefs, unlike the competing new Mystery Religions that appeared in the Roman Empire at the same time. Early Christianity also encouraged education and literacy among its followers so that they could read and understand the scriptures, this permitted many christians to be hired into the bureaucracy of the Roman Empire, even at times when the Empire made Christianity illegal.
Christianity did not easily spread through the Roman Empire. See the related question, "How did Christianity spread throughout the Roman Empire?"
The roman empire itself. But disciples like Paul assisted in spreading the gospel.
The spread of Christianity had political ramifications for the Roman Empire. The empire split into two, Constantinople to the east and Rome to the west
There was no one particular person who spread Christianity throughout the empire. All of the disciples/apostles of Jesus went out to "teach all nations". Several apostles are patrons of distant countries and they may very well have traveled to them. For example, James is affiliated with Spain, Peter with Rome, Luke, although not an apostle but a friend of Paul, is buried in Padua, Italy according to the latest DNA. Paul himself traveled and wrote throughout the middle east until he was taken to Rome as a prisoner. The Roman Emperor Constantine also helped spread Christianity by declaring it the official religion of the Roman Empire.
They attracted visitors to Constantinople merchant came to trade the byzantine people liked to show off their wealth and they impressed their visitors by ceremonies, glittering jewels and some rich clothes. The visitors brought all the products home with them to show others.
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Christianity did not easily spread through the Roman Empire. See the related question, "How did Christianity spread throughout the Roman Empire?"
1018
By 325ad Christianity had spread throughout the Roman Empire and to Britain. If you google "spread of Christianity map" you will find maps showing the spread.
Constantine
More than anyone before him, Emperor Constantine spread Christianity throughout the Roman Empire. True, Christianity was already well established, especially in the Greek-speaking east, long before the fourth century, but Constantine gave the religion state patronage, offered career preferment to those who claimed to be Christians, and began the long persecution of the pagan temples. From this time, and with this impetus, Christianity spread quickly in the Roman Empire.
More than anyone before him, Emperor Constantine spread Christianity throughout the Roman Empire. True, Christianity was already well established, especially in the Greek-speaking east, long before the fourth century, but Constantine gave the religion state patronage, offered career preferment to those who claimed to be Christians, and began the long persecution of the pagan temples. From this time, and with this impetus, Christianity spread quickly in the Roman Empire.
There was not one person who spread Christianity throughout the Roman empire. Christianity began its expansion by the efforts of the original apostles and Paul. These men gained followers who in turn gained followers and the movement snowballed.
The Romans who remained pagans did not contribute to the spread of Christianity Neither did Julian, who was the only pagan emperor in the Later Roman Empire
The apostles and Paul traveled throughout the region teaching others.
As Roman Emporer, Constantine declared Christianity to be the official religion of the Roman Empire. At the time, the Empire was vast, so Christianity spread quickly.
There was no single person who spread Christianity throughout the empire. Each one of the apostles of Jesus went to different areas to preach. Paul also did a lot of writing and traveling and converting.