How old is the child? What subjects in particular are you concerned about? I will be able to give more specific recommendation if you outline what your needs are.
There are indeed practically no secular homeschooling curriculum packages out there. Secular homeschoolers do not seem to need them, therefore, none are offered.
Religious curriculum packages, such as Sonlight, unite all subjects under an umbrella of a religious view, including subjects that should be belief-neutral, like math. They are meant for people for whom religious indoctrination is number one reason to home school. They value being able to easily tie everything they learn with God's plan or whatever. That's what a curriculum provides. In my view though, no matter what one's beliefs are, following a full prepackaged curriculum takes away the fun of following your child's interests and potential, which is what homeschooling is all about.
Building your own program is a bit more time consuming, but easy and rewarding. There is a wealth of options available. You can do an online search or visit a local educational materials store. Both subject curriculums and enriching literature (non-fiction books, games) can be used. My kids are in elementary school. For us, it works to stick with a curriculum for math and language arts, use a variety of non-fiction books for science and social studies, and read whatever fiction strikes our fancy. Older children may need a more structured approach, but at that point you may be looking at some online classes, too, to supplement your home learning.