Secular homeschool curriculum is hard to find, I know this because I am looking for it too. I am looking for Canadian secular curriculum which is even rarer.
But it is out there, you just have to look, or scroll farther down this page for secular history curriculum.
only discusses religious beliefs from an anthropological perspective. It is not faith-neutral (this becomes important especially when discussing science and history curricula). It does not posit biblical/religious beliefs as historical facts.