The historian faces formidable foes. While he judges the past with impunity, he may be found wanting when future generations judge him in their own histories (Herodotus has been called both “the Father of History” and the “Father of Lies”). Eusebius, the first Church historian, was guilty of heresy, not mere lying. He did not belong to a fringe or radical group—at the time Arians formed the majority party. In our democratic age it seems downright unfair to charge a man with heresy for betting on the then-winning team. But truth is undemocratic, and the faith of Athanasius contra mundum prevailed.
This danger, however, is not strictly historical. Eusebius’ Arianism is bad theology, not bad history. Christian theologians face a problem at the heart of history itself. Simply put: How do we understand history? We believe in a God made flesh, who entered history at a very specific point—“in those days… [when] there went out a decree from Caesar Augustus… when Cyrenius was governor of Syria” (Lk 2:1–2). C.S. Lewis famously called this a myth become fact:
The old myth of the Dying God, without ceasing to be a myth, comes down from the heaven of legend and imagination to the earth of history. It happens—at a particular date, in a particular place, followed by definable historical consequences.
However, this suggestive description of the incarnation leaves the question of history itself unresolved. “The world has become mingled with God” (St. Isaac of Syria), but how do we describe such a world?
On the one hand, the Christian view of history has no choice. It must distinguish itself from an exclusively secular view of history. As Vladimir Lossky cautions:
For the ‘historian of the Church’ the religious factor disappears and finds itself displaced by others; such… as the play of political or social interests, the part played by racial or cultural conditions, considered as determining factors in the life of the Church. We think ourselves shrewder, more up to date, in invoking these factors as the true guiding forces of ecclesiastical history. While recognizing their importance, a Christian historian can scarcely resign himself to regarding them otherwise than as accidental to the essential nature of the Church.
This insight is key, but requires a further warning, provided by Fr. Georges Florovsky:
The Christian historian will attempt to reveal the actual course of events in the light of his Christian knowledge of man, but will be slow and cautious in detecting the “providential” structure of actual history, in any detail. Even in the history of the Church “the hand of Providence” is emphatically hidden, though it would be blasphemous to deny that this Hand does exist or that God is truly the Lord of history. Actually, the purpose of a historical understanding is not so much to detect the Divine action in history as to understand… human activities, in the bewildering variety in which they appear to a human observer.
We must achieve a delicate balance, lest our thinking devolve into mere skeptical worldliness or credulity that borders upon superstition. By following this royal road we can begin to examine the long and complex history of the Orthodox Church’s relation to the state.
 From “Myth Became Fact,” God in the Dock, pg 66–67 (Eerdmans: Grand Rapids, MI).
 The Prayers of Saint Isaac the Syrian, pg 18 (Divine Ascent Press: Manton, CA). Quoted by Met. Hilarion Alfeyev in “The Incarnation of the Word and the deification of man according to St Isaac of Ninevah” (http://orthodoxeurope.org/page/11/1/16.aspx).
 Mystical Theology of the Eastern Church, pg 13 (St. Vladimir’s Seminary Press: Crestwood, NY).
 Quoted by Jaroslav Pelikan in “The Predicament of the Christian Historian” (http://jtlth.blogspot.com/2008/05/predicament-of-christian-historian1.html).