Being a Secular Homeschooler can be a bit tough sometimes. I know that many Secular Homeschoolers have issues with being in the minority, feeling left out & isolated. I really don't have a problem with that, since I have never fit in anyway & have always been in the minority.
No, my problem is with finding the right curriculum. You see, sometimes the best curriculum, for a specific subject, is a religious one. It's unfortunate, but it's the way things are. There really is such a limited selection of high-quality secular materials. So, some use religious materials and secularize them. Others stick only to secular materials, even if it means lower quality. Still others piece together their curriculum with whatever secular supplemental materials they can find or create it themselves.
I do a combination. There are some subjects for which I will not use a religious based curriculum, no matter what. The main ones are Science and Social Studies (I know that some homeschoolers have issues with the term Social Studies, but I consider it to be an umbrella term that encompasses History, Geography, & Cultural Studies). For Social Studies, we don't use much formal curriculum anyway. Geography is the only part of Social Studies for which we use formal curriculum. For History & Cultural Studies we have a plan, a formula, that we follow. We use a huge variety of supplemental materials, including some I create myself. For Geography, we use a formal curriculum as a spine & add tons of supplements. I think I do that because I feel that the Geography education I got in school was so lacking, I want to make sure that my kids get better. Geography, though, isn't an area that is difficult to find secular curriculum.
For Science, we don't use formal curriculum until high school level. Before high school level, our Science is done the same way our History is, I piece it together with supplemental materials (including some I create myself). Once we do use formal curriculum, I would rather choose a lower quality secular curriculum, that I can supplement to make more comprehensive & higher quality, than get a high quality religious curriculum that I will have to edit, omit things from, and supplement to make up for all the stuff I had to remove from it.
There are some subjects, though, where I am willing to secularize a religious curriculum, if it is a better fit & requires less tweaking than any secular material I've found. Math is one of these. Both my kids have used a non-secular curriculum for Math. Life of Fred is technically not a secular curriculum. However, it's not preachy and doesn't push religion. It doesn't have Bible quotes throughout. Plus, it made my daughter, the Math hater, enjoy Math & see that it really is useful in everyday life. That is something no other Math curriculum ever did. Mastering Mathematics isn't peppered throughout with Bible passages, but does have religion in it, especially in certain sections. However, it is a Mastery program, a true Mastery program (one that actually focuses on just ONE concept at a time). Most of the programs people call Mastery programs don't focus on mastery of just one concept, they introduce several concepts in each grade & cover them repeatedly in each grade until you have them, this is the way a spiral program works, not a mastery program. The few others that actually could be considered mastery, I don't like. So, even though it is a religious program, it is the best program to meet our needs & my requirements. I would rather skip the religious comments, use something else for Graphing (it's most religious area), and supplement with the Key to series for Measurement & Metric Measurement (an area I think is lacking a bit in Mastering Mathematics, at least so far), than go with something that doesn't allow us to focus on one concept at a time or that teaches Math in a way we don't like.
In a foreign language program, I don't mind the occasional translation of a Bible passage or story. I also wouldn't mind the occasional religious reference in an English/Language Arts program. Maybe it's because so many of the people in our life are Christian, or maybe it's the cultural relevance, or the fact that we make sure they learn about all religions & allow them to choose their own religious path (or lack there of), but I don't expect my kids to avoid all religious references. So, an occasional reference isn't a big deal to me. Constant references, Bible passages in every lesson, expecting you to graph things from the Bible, explaining that you should be frugal with money because that is what God wants you to do, those are the kind of things I don't want in our materials. Those are the things I will skip over. Those are the things that will cause me to not purchase a material, even if it means going with something less comprehensive or lower quality, if it is too pervasive to skip over.
What it comes down to is this: I homeschool to give my kids the best education possible. If the best material for a certain subject is a religious material, that I can tweak to fit our needs, I will use it & secularize it. I would rather have to tweak or supplement something than give my kids a half-assed education. I will not use a material that doesn't work for us, just because it is completely secular, if there is a religious material that will work better with just some tweaking or omitting the religious content. That would be doing my kids a disservice.
So, that's where I stand on secularizing curriculum.