(commonly known simply as 'Orosius') lived in the 5th century CE and was a Christian theologian and historian of note and also a close friend of St. Augustine. He is best known for his work Seven Books of History Against the Pagans in which he argued, primarily, that the fall of Rome
had nothing to do with the Roman
adoption of Christianity
(a claim popularly supported among the pagans of the day). This work was the first world history by a Christian and was completed in 418 CE, shortly after the sack of Rome by Alaric in 410.
Using material taken from Livy, Caesar, Tacitus, Justin, and others (who were all pagans) as well as Suetonius, Florus, Justin, the Holy Scripture and the History of the Church by Eusebius, Orosius supported his claim that Christianity had done more good than harm and, certainly, had no hand in the decline and fall of the Roman Empire
. Orosius argued strongly that his anti-Christian opposition had no tenable ground by giving specific examples and illustrations of cultural calamities that happened long before the rise of Christianity. His work was very popular and, owing to his friendship with St. Augustine, was accepted easily by the early church as 'true' history and, eventually, found its way into the accepted history of the fall of the Roman Empire
until Edward Gibbon published his famous six-volume The History of the Decline and Fall of the Roman Empire (between 1776 and 1788 CE) which presented a vastly different view of the situation and has, since, influenced other historians to re-evaluate Orosius' interpretation of earlier sources. Even so, Orosius remains an important writer of his time and his work is still often referenced in theological, philosophical and historical works.