Disunion in the Roman Empire contributed to disunion in the Church. Theodosius the Great, who in 380 established Nicene Christianity as the official religion of the Roman Empire (see Edict of Thessalonica), was the last Emperor to rule over a united Roman Empire. Following the death of Theodosius in 395, the Empire was divided for the final time into western and eastern halves. In the 4th century, the Roman emperor (reigning in Constantinople) started to control the Church in his territory.