Okay, I did some research into it.
Praeparatio Evangelica XII, the book in question (and the previous book as well, might I add), talked alot about Plato and common philosophical ideas at the time. Bishop Eusebius, in this part of his book series, was comparing and contrasting some of the ideas presented. The title was actually an idea proposed by Plato that Bishop Eusebius utilized.
Here's the actual content of that chapter (by the way, chapter 31 is the correct chapter under that title, as chapter 32 was entitled "That not men only, but also women and every race of mankind, ought to be admitted to the education above described"):
"CHAPTER XXXI
[PLATO]
100 'But even if the case were not such as our argument has now proved it to be, if a lawgiver, who is to be of ever so little use, could have ventured to tell any falsehood at all to the young for their good, is there any falsehood that he could have told more beneficial than this, and better able to make them all do everything that is just, not by compulsion but willingly?
'Truth, O Stranger, is a noble and an enduring thing; it seems, however, not easy to persuade men of it.'
Now you may find in the Hebrew Scriptures also thousands of such passages concerning God as though He were jealous, or sleeping, or angry, or subject to any other human passions, which passages are adopted for the benefit of those who need this mode of instruction.* "
(The Tertullian [translation] Project
http://www.tertullian.org/fathers/eusebius_pe_12_book12.htm)
As you can see, the context in which he was using the word "lie" isn't fabrication, but more kin to the likes of a parable. As he pointed out, God isn't affected by jealousy, but the word jealous is used so that we may understand. The Bishop wasn't saying that "making things up about the divine was right and justified because it made people moral", but more in line of "convey the message so that they that cannot understand such things understand and then apply it".
The controversy over the passage started with a comment by Edward Gibbon, but that's another story.
However, like it or not... with man, there is always sin. So to say that any of the early church fathers or clerics could have never sinned would be a mistake.
God bless.
Added in edit: Notation 100 after [Plato] refers to
d 1 Plato, Laws, 663 D.
*I have bolded the Bishop's comment as to seperate it from the statement by Plato.
