What does "every scripture is God-breathed" (θεόπνευστος) mean?

In my reading, I came across this quote a couple of days ago, from the pen of C.S. Lewis in his book, Reflections on the Psalms (p. 47 Kindle ebook).

"The human qualities of the raw materials show through. Naivety, error, contradiction, even (as in the cursing Psalms) wickedness are not removed. The total result is not 'the Word of God' in the sense that every passage, in itself, gives impeccable science or history. It carries the Word of God; and we (under grace, with attention to tradition and to interpreters wiser than ourselves, and with the use of such intelligence and learning as we may have) receive that word from it not by using it as an encyclopedia or an encyclical but by steeping ourselves in its tone or temper and so learning its overall message.

To a human mind this working-up (in a sense imperfectly), this sublimation (incomplete) of human material, seems, no doubt, an untidy and leaking vehicle. We might have expected, we may think we should have preferred, an unrefracted light giving us ultimate truth in systematic form--something we could have tabulated and memorized and relied on like the multiplication table. One can respect, and at moments envy, both the Fundamentalist's view of the Bible and the Roman Catholic's view of the Church. But there is one argument which we should beware of using for either proposition: God must have done what is best, this is best, therefore God has done this. For we are mortals and do knot know what is best for us, and it is dangerous to prescribe what God must have done--especially when we cannot, for the life of us, see that He has after all done it."

In his book, The Bible Tells Me So: Why Defending Scripture Has Made Us Unable to Read It, Peter Enns states, "Many Christians have been taught that the bible is Truth downloaded from heaven, God's rulebook, a heavenly instructional manual--follow the directions and out pops a true believer; deviate from the script and God will come crashing down on you with full force...What I discovered, and what I want to pass along to you in this book, is that this view of the Bible does not come from the Bible but from an anxiety over protecting the Bible and so regulating the faith for those who read it...When you read the Bible on its own terms, you discover that it doesn't behave itself like a holy rulebook should. It is definitely inspiring and uplifting...But just as often it's a challenging book that leaves you with more questions than answers."

Rereading Genesis and Exodus has been a challenging read for me. I feel like I need to defend some of its stories, whether they are accounts of what actually happened, historical fiction or stories that are more parabolic in nature. There are inconsistencies in details. There are moral choices that are at best questionable and at times downright evil of which the main characters, the ancestors of the Israelites, are guilty and seemingly unrepentant. But as both Lewis and Enns note, that doesn't mean I am going to throw the baby out with the bath water. Over the last few years, my understanding of inspiration has changed and thus the way I view the Bible has changed. I still love it, I still read it, I still strive to put its principles into practice in my life and I still teach it to others, because (again to quote Enns), "...I meet God in its pages...[and] I want to help others meet God, too."