Which helped the spread of both Roman Catholicism and Orthodox Christianity?

Answer 1

The Roman Empire helped the spread of Catholicism and Orthodox Christianity.

Christianity was preached around the eastern part of the Roman Empire by the apostles and other missionaries. Churches developed and the Patriarchates of Antioch, Alexandria and, later, Constantinople were established. The main kind of Christianity which developed in the eastern part of the Roman Empire was called Greek or Eastern Christianity. Later it came to be called Orthodox Christianity.

Catholicism was initially called Latin or Western Christianity and became the main for of Christianity in the western part of the Roman Empire. It originated from theologists in Roman Tunisia and soon reached italy.

Although Christianity was persecuted by the Romans for a period of time, mainstream Christianity (Greek and Latin Christianity) was made the sole legitimate religion of the empire by the Edict of Thessalonica issued in 380 by the co-emperors Theodosius I and Gratian. The purpose of the edict was to ban dissident Christian doctrines, which were branded as heretic and persecuted. The main target was Arian Christianity, which was popular around the empire.