 In medieval times , when the Roman Catholic Church was dominant , Catholic historians presented Constantine as an ideal ruler , the standard against which any king or emperor could be measured . The Renaissance rediscovery of anti @-@ Constantinian sources prompted a re @-@ evaluation of Constantine 's career . The German humanist Johann Löwenklau , discoverer of Zosimus ' writings , published a Latin translation thereof in 1576 . In its preface , he argued that Zosimus ' picture of Constantine was superior to that offered by Eusebius and the Church historians , and damned Constantine as a tyrant . Cardinal Caesar Baronius , a man of the Counter @-@ Reformation , criticized Zosimus , favoring Eusebius ' account of the Constantinian era . Baronius ' Life of Constantine ( 1588 ) presents Constantine as the model of a Christian prince . For his History of the Decline and Fall of the Roman Empire ( 1776 – 89 ) , Edward Gibbon , aiming to unite the two extremes of Constantinian scholarship , offered a portrait of Constantine built on the contrasted narratives of Eusebius and Zosimus . In a form that parallels his account of the empire 's decline , Gibbon presents a noble war hero corrupted by Christian influences , who transforms into an Oriental despot in his old age : " a hero ... degenerating into a cruel and dissolute monarch " . 
