Eusebius is often regarded as the first court appointed Christian theologian in the service of the Constantine Roman Empire, seeing the Empire and the Imperial Church as closely bonded.
http://www.britannica.com/shakespeare/article-67584 Notwithstanding the great influence of his works on others, Eusebius was not himself a great historian.
http://www.britannica.com/eb/article-9033282 His treatment of heresy, for example, is inadequate, and he knew very little about the Western church. His historical works are really apologetics. In his Ecclesiastical History, Vol. 8, chapter 2, he points out, "We shall introduce into this history in general only those events which may be useful first to ourselves and afterwards to posterity."
In his
Praeparatio evangelica (xii, 31), Eusebius has a section on the use of fictions (
pseudos) as a "medicine", which may be "lawful and fitting" to use
http://www.tertullian.org/rpearse/eusebius/pe_data.htm. With that in mind, it is still difficult to assess Eusebius' conclusions and veracity by confronting him with his predecessors and contemporaries, for texts of previous chroniclers, notably
Papias, whom he denigrated, and
Hegesippus, on whom he relied, have disappeared; they survive largely in the form of the quotes of their work that Eusebius selected and thus they are to be seen only through the lens of Eusebius.
These and other issues have invited controversy. For example, Jacob Burckhardt has dismissed Eusebus as "the first thoroughly dishonest historian of antiquity". and was not alone in holding such a view. He has also been accused of dishonesty at various times, and in various connections by other historians:
*Gibbon dismissed his testimony on the number of martyrs and impugned his honesty by referring to a passage in the
Ecclesiastical History, book 8, chapter 2, in which Eusebius introduces his discussion of the Great Persecution under Diocletian with: "We shall introduce into this history in general only those events which may be useful first to ourselves and afterwards to posterity."
*Gibbon also pointed out that the chapter heading in Eusebius'
Praeparatio evangelica (xii, 31), says how fictions (
pseudos) — which Gibbon rendered 'falsehoods' — may be a "medicine", which may be "lawful and fitting" to use
http://www.tertullian.org/rpearse/eusebius/pe_data.htm. But the text is discussing parallels between the Bible and the theories of Plato on education, and Eusebius is suggesting that the Bible also contains such material. Unless it is supposed that Eusebius believes the Bible to be deceptive, it is easy to see why Gibbon confined his remark to the chapter heading (which may not be authorial anyway), and why Gibbon was accused of dishonesty in his attacks on Eusebius. However, it can also be argued that Eusebius would logically have the same thinking when it came to politics, if this was his opinion about mere interpretations of the Bible.
*Questions were long raised by scholars about whether all the documents in the
Life of Constantine were authentic.
But other views have tended to prevail.
*Joseph Lightfoot rebutted the arguments of Gibbon
http://www.tertullian.org/rpearse/eusebius/lightfoot.htm, pointing out that Eusebius' very frank statements indicate his honesty in stating what he was not going to discuss, and also his limitations as a historian in not including such material. He also discusses the question of accuracy. "The manner in which Eusebius deals with his very numerous quotations elsewhere, where we can test his honesty, is a sufficient vindication against this unjust charge." But he accepts that Eusebius cannot always be relied on. "A far more serious drawback to his value as a historian is the loose and uncritical spirit in which he sometimes deals with his materials. This shews itself in diverse ways. (a) He is not always to be trusted in his discrimination of genuine and spurious documents."
*G. A. Williamson has written, "Gibbon's notorious sneer ... was effectively disposed of by Lightfoot, who fully vindicated Eusebius' honour as a narrator 'against this unjust charge'."
*Averil Cameron and Stuart Hall, in their recent translation of the
Life of Constantine point out that writers such as Burckhardt found it necessary to attack Eusebius in order to undermine the ideological legitimacy of the Hapsburg empire, which based itself on the idea of Christian empire derived from Constantine, and that the most controversial letter in the
Life has since been found among the papyri of Egypt.
*Michael J. Hollerich, replying to Burckhardt's criticism of Eusebius, thinks that criticisms goes too far. Writing in "Church History" (Vol. 59, 1990), he says that ever since Burckhardt, "Eusebius has been an inviting target for students of the Constantinian era. At one time or another they have characterized him as a political propagandist, a good courtier, the shrewd and worldly adviser of the Emperor Constantine, the great publicist of the first Christian emperor, the first in a long succession of ecclesiastical politicians, the herald of Byzantinism, a political theologian, a political metaphysician, and a caesaropapist. It is obvious that these are not, in the main, neutral descriptions. Much traditional scholarship, sometimes with barely suppressed disdain, has regarded Eusebius as one who risked his orthodoxy and perhaps his character because of his zeal for the Constantinian establishment." He concludes that "the standard assessment has exaggerated the importance of political themes and political motives in Eusebius's life and writings and has failed to do justice to him as a churchman and a scholar".
While many have shared Burckhardt's assessment, particularly with reference to the
Life of Constantine, others, while not pretending to extol his merits, have acknowledged the irreplaceable value of his works. The value of his works has generally been sought in the copious quotations that they contain from other sources, often lost.