Regarding published curricula, I certainly agree that a search for one that "teaches exactly what you believe across the board" is unrealistic. In the realm of science, I don't know the subject well enough to define what that standard would be, and I think I'm enough of an open-minded learner that it would be a perpetually moving target.
That said, what I want to avoid with science materials are any that are developed with some purpose other than to provide the most accurate, age-appropriate scientific content. So, for example, when a Human Anatomy and Physiology textbook from Apologia states on the back cover that "sections entitled 'Creation Confirmation' provide evidence for young-earth creationism in the context of the topic that the students are studying," it reveals an agenda that is at least supplemental to—and I believe in opposition to—teaching good science. The same text, in a section entitled "Apes and Apemen," includes the following quotes:
"As you may know, some science books teach students the absurd notion that people are just advanced animals simply because people have some things in common with apes."
"They believe that over many, many, many generations, those advancements 'piled up,' turning apes into humans."
"However, even though mutations are never positive, evolutionists believe that apes turned into men because of millions of positive mutations piling up over the years!"
"Scientific studies have shown over and over again that mutations are never positive for any species."
"There is no evidence for ."
I'm open to correction from practicing scientists if I'm wrong here, but my understanding is that no one with professional knowledge of evolutionary science would find any of these statements to be accurate. My conclusion is that they can only be the product of someone who is thoroughly ignorant of evolutionary science (and therefore ought not to be authoring an Anatomy and Physiology textbook) or who is trying to promulgate an insidious caricature of the Theory of Evolution.
So, in my view the key issue is ideology. I believe Chris' thoughts are spot-on here:
I've lightly glanced through the rest of the A&P textbook I quoted above, and it may well have some quality content in it. But the admitted, underlying YEC ideology has poisoned the well for me; I don't want to spend time sifting through what content in the book is tainted and what is not. I prefer to just find a better book.
I intend to respond more to Christy's inquiry (from her initial response) about what resources and textbooks CC uses at the Challenge level, but I do know that Apologia science books are part of it, which is one reason I provided the details I did above.
The publisher that I am most enthusiastic and hopeful about is Novare Science and Math. I first learned of them through the BioLogos resources page, and Christy mentioned them briefly in her excellent overview of homeschool science materials. The founder, John Mays, spoke at the BioLogos conference last Summer. I have exchanged emails with the author of their recently completed Earth Science textbook, Kevin Nelstead, who has some great resources at his GeoChristian site, and I'd like to have my son start working through this book once the CC year finishes in a few weeks. I love just about everything in Novare's textbook philosophy page, and I'm hopeful that they may provide a suitable supplement or replacement to the CC science materials for as long as we stay with their program. I believe Novare intends to publish a biology textbook at some point in the future, and I'm sure there will be a lot people eager to see how that turns out.
If anyone has any "hands-on" experience with Novare texts—particularly in a homeschool setting, I would love to hear your thoughts about them. I've gathered that they are primarily used in private schools, but Jeffrey Mays (John's brother) has assured me that "there are many homeschoolers using our texts just fine."