<P> The remarkable transformation of Christianity from peripheral sect, to major force within the Empire is illustrated by the influence held by St Ambrose, the Bishop of Milan . A Doctor of the Church and one of the most influential ecclesiastical figures of the 4th century, Ambrose became a player in Imperial politics, courted for his influence by competing contenders for the Imperial throne . When the Emperor Theodosius I ordered the punitive massacre of thousands of the citizens of Thessaloniki, Ambrose admonished him publicly, refused him the Eucharist and called on him to perform a public penance, a call to which the Christian Emperor submitted . While paganism in the Roman Empire was not yet finished, the episode prefigured the role of the Church in the political life of Europe in coming centuries . </P> <P> Theodosius reigned (albeit for a brief interim) as the last Emperor of a united Eastern and Western Roman Empire . In 391 Theodosius sought to block the restoration of the pagan Altar of Victory to the Roman Senate and then fought against Eugenius, who courted pagan support for his own bid for the imperial throne . Thus, the Catholic Encyclopedia lauds Theodosius as: </P> <P> (O) ne of the sovereigns by universal consent called Great . He stamped out the last vestiges of paganism, put an end to the Arian heresy in the empire, pacified the Goths, left a famous example of penitence for a crime, and reigned as a just and mighty Catholic emperor . </P> <P> During the fourth century, Christian writing and theology blossomed into a "Golden Age" of literary and scholarly activity unmatched since the days of Virgil and Horace . Many of these works remain influential in politics, law, ethics and other fields . A new genre of literature was also born in the fourth century: church history . </P>

Who made the greatest contribution toward spreading christianity