Theodosius II was the emperor of the Holy Eastern Roman Empire and law-maker. Published Theodosian Code 438 AD. This Code represents the updating of a collection of laws published after 312 AD by the Christian Emperors. According to this code, Christianity becomes a state religion and replaces paganism in the eastern and western countries of Byzantium.
Hence, the first consequence is Christianity is the official religion of the empire.
Secondly, the Church has the power to interfere in state affairs and the power of decision-making at the state level and therefore realizes superiority over the state.
Thirdly, all other religions become banned and all of their followers are often labeled as heretics.