In my last post, I mentioned Jon Curry's argument that Eusebius advocated lying. I cited Roger Pearse's material responding to the accusation, and I've added more material of my own elsewhere. For example, the historian Paul Maier, in his translation of Eusebius' church history, refers to Eusebius as "scrupulously honest not only in acknowledging his sources but also in confessing the trepidation with which he undertook his task" (Eusebius - The Church History [Grand Rapids, Michigan: Kregel Publications, 1999], p. 17). The patristic scholar John McGuckin refers to "his high and honest regard for the ancient documents" (The Westminster Handbook To Patristic Theology [Louisville, Kentucky: Westminster John Knox Press, 2004], p. 128). "If Eusebius' interpretation of these documents [used in his church history] was sometimes in error, this is to be explained by his want of critical judgement and not by conscious perversion of the facts." (F.L. Cross and E.A. Livingstone, editors, The Oxford Dictionary Of The Christian Church [New York: Oxford University Press, 1997], p. 574) Roger Pearse also cites the comments of some other scholars, including the highly regarded patristic scholar J.B. Lightfoot.
There's a lot of Eusebius' material that I haven't read. And he surely was dishonest to some degree or another at times in his life, perhaps in some places in his writings. You've probably heard of Bob Woodward's recent book on the Bush administration and the situation in Iraq, and the people responding to that book and the issues surrounding it have been making accusations back and forth about the motives and accuracy of both sides. I saw a member of the Bush administration interviewed on television this morning, and he didn't want to accuse Woodward of lying or even of "having an agenda", but he did suggest that Woodward had some bias and wasn't as careful as he should have been. People will make accusations back and forth about differing degrees of bias, carelessness, dishonesty, etc. on both sides of the dispute. But it's doubtful that many people, if any, from either side will accuse the other side of publicly advocating the practice of lying. That's the charge that's been brought against Eusebius. Supposedly, he publicly advocated lying in book 12 of The Preparation Of The Gospel. It's not a matter of whether Eusebius was biased in some sense, was sometimes careless, was sometimes wrong, etc., as other ancient and modern sources often have been.
In addition to repeating Richard Carrier's suggestion that Eusebius advocated lying, Jon Curry has repeated the suggestion that the passage in Josephus about Jesus may have been interpolated by Eusebius. (Jon does this a lot. He comes across an argument against Christianity, doesn't do much to research it, then mentions it in a discussion with a Christian. When he's corrected, he doesn't seem to learn much from the experience, because he keeps doing it.) See Chris Price's article on the Josephus passage here and his article about whether Eusebius interpolated the passage here.
Below are some comments Eusebius made about honesty. Many of these comments are made in the context of discussing whether it's likely that Jesus' disciples would have lied about Him. Note how he refers to the evil nature of lying, how God cannot lie, etc. Notice that the second quote below comes from the same work in which Eusebius supposedly advocated lying.
"I would ask, then, where would be the sense in suspecting that hearers of such teaching, who were themselves masters in such instruction, invented their account of their Master's work? How is it possible to think that they were all in agreement to lie, being twelve in number especially chosen, and seventy besides, whom He is said to have sent two and two before His face into every place and country into which He Himself would come? But no argument can prove that so large a body of men were untrustworthy, who embraced a holy and godly life, regarded their own affairs as of no account, and instead of their dearest ones ----I mean their wives, children, and all their family----chose a life of poverty, and carried to all men as from one mouth a consistent account of their Master. Such would be the right and obvious and true argument; let us examine that which opposes it. Imagine the teacher and his disciples. Then admit the fanciful hypothesis that he teaches not the aforesaid things, hut doctrines opposed to them, that is to say, to transgress, to be unholy, to be unjust, to be covetous and fraudulent, and anything else that is evil; that he recommends them to endeavour so to do without being found out, and to hide their disposition quite cleverly with a screen of holy teaching and a novel profession of godliness. Let the pupils pursue these, and more vicious ideals still, with the eagerness and inventiveness of evil: let them exalt their teacher with lying words, and spare no falsity: let them record in fictitious narrative his miracles and works of wonder, so that they may gain admiration and felicitation for being the pupils of such a master. Come, tell me, if such an enterprise engineered by such men would hold together? You know the saying, 'The rogue is neither dear to rogue nor saint.' Whence came, among a crew of so many, a harmony of rogues? Whence their general and consistent evidence about everything, and their agreement even unto death?...[quoting what the apostles would say if they were deceivers] 'This is our prize, to go straight in the teeth of all the nations, to war on the gods that have been acknowledged by them all for ages, to say that our Master, who was crucified before our very eyes was God, and to represent Him as God's Son, for Whom we are ready to die, though we know we have learned from Him nothing either true or useful. Yes, that is the reason we must honour Him the more----His utter uselessness to us----we must strain every nerve to glorify His name, undergo all insults and punishments, and welcome every form of death for the sake of a lie. Perhaps truth is the same thing as evil, and falsehood must then be the opposite of evil. So let us say that He raised the dead, cleansed lepers, drove out daemons, and did many other marvellous works, knowing all the time that He did nothing of the kind, while we invent everything for ourselves, and deceive those we can. And suppose we convince nobody, at any rate we shall have the satisfaction of drawing down upon ourselves, in return for our inventions, the retribution for our deceit.' Now is all this plausible? Does such an account have the ring of truth? Can any one persuade himself that poor and unlettered men could make up such stories, and form a conspiracy to invade the Roman Empire? Or that human nature, whose characteristic clement is self-preservation, would ever be able for the sake of nothing at all to undergo a voluntary death? or that our Saviour's disciples reached such a pitch of madness, that, though they had never seen Him work miracles, they with one consent invented many, and having heaped together a mass of lying words about Him were ready to suffer death to uphold them?" (The Proof Of The Gospel, 3:5)
"And then the fact that even in simple sayings and common conversation they are not indifferent, but carefully measure their words even in these, so as to utter by their voice no lie, nor railing, nor any foul and unseemly word, because again of His admonition, wherein He said, 'for every idle word ye shall give account in the day of judgement'—to what a high degree of philosophic life do these things pertain?...For how could the divine ever speak falsely, being in nature most truthful, since surely the divine is truthful? And how could a good daemon ever deceive the inquirers by false statements? Or how could that which is 'fettered' by the course of the stars be superior to man? Nay, a mortal man who paid any little regard to virtue would never lie, but would choose rather to reverence the truth; nor would he lay the blame of a lie upon any necessity of fate or course of the stars....[quoting Origen with approval] 'If, however, any one shall explain the expression, 'It will certainly be,' by saying that though certain events will be in accordance with its indication, yet that it was possible also for it to have been otherwise, this we admit as true. For though it is 'not possible that God should lie,' yet it is possible, concerning things that may either happen or not happen, that He should know either that they will happen or that they will not happen.'" (The Preparation Of The Gospel, 1:4, 6:6. 6:11)