I regularly read Maureen Wittman as well as own several of her publications. At times folks have questioned why I don't use all Catholic materials and I've never been able to explain myself well. I found the answer on Maureen's blog:
"One final note, it would be impossible to give my children a solid education if I only used books by Catholics, completely free of error. It would mean leaving out Dickens and Lewis. It would mean skipping Ancient Rome and Ancient Greece. The important thing to me is to present these books to my children baptized in the Catholic Faith -- giving them Church teaching on issues that come up as we read. Issues they will be faced with when they go out into the real world."