Theodosius I in Wikipedia

Flavius Theodosius (11 January 347 – 17 January 395), commonly known as Theodosius I or Theodosius the Great, was Roman Emperor from 378 to 395. Theodosius was the last emperor to rule over both the eastern and the western halves of the Roman Empire. During his reign, the Goths secured control of Illyricum after the Gothic War - establishing their homeland south of the Danube within the empire's borders. He is known for making Nicene Christianity the official state religion of the Roman Empire, [1] issuing decrees that effectively worked towards melding the Roman state and the Christian Church into a single de facto church-state entity.[2] He is recognized by the Eastern Orthodox Church as Saint Theodosius. He defeated the usurpers Magnus Maximus and Eugenius and fostered the destruction of some prominent pagan temples: the Serapeum in Alexandria, the Temple of Apollo in Delphi, and the Vestal Virgins in Rome. After his death, Theodosius' sons Arcadius and Honorius inherited the East and West halves respectively, and the Roman Empire was never again re-united...