I was raised a Southern Baptist in Germany (Dad was Army). We were SO SBC that we even helped some with church planting and the missionaries in charge of that were close family friends.
That said, my parents felt it was of the utmost importance that we learned about the world in which we lived, so when we visited Turkey, we learned about Islam and toured the mosques. We respected the prayer times and customs. When we were in Israel, we learned about Jewish customs and visited the synagogues. When in England, we attended Anglican worship, when in Spain, we attended Catholic worship. When in Greece, we learned about the Greek gods and their place in the understanding of the times.
Aside, funny story: Poseidon got me suspended from the 3rd grade! Upon returning to school, we had the obligatory "What I Did This Summer" essay (along with illustration). I wrote about our travels through Turkey, Bulgaria, and Greece, but am NO artist. As such, I copied a picture from a book that included a photo of a statue of Poseidon we had seen, only, being a 3rd grader, I enhanced a certain part of his anatomy a bit.

I still remember the thudding sound my 3rd grade teacher made before she hauled me down to the principal's office as a pornographer (and I had NO idea what that even was...) Happily, he was a friend of the family and as well-travelled so after the parent meeting, I was allowed back to class without having to wear a red "P" on my shirt for the rest of the year.

I will say, I almost fell down the stairs of the Adventurer's Club at Downtown Disney the first time I set eyes on THAT statue (only their version is family-friendly and not AT ALL like the real thing...)
OK, back to the point. My parents weren't afraid that by learning, we would lose our faith. They were giving us definitions for what we believe. Granted, we were still being hit with the "A praying leg and a dancing foot don't grow on the same leg" speech

, but we were able to make up our own minds. Now that we are adults, it's very interesting to see how diverse our own belief systems have become based on our upbringing. I'm definitely the rebel in the clan, but that could be b/c I'm also the only girl...
I feel for those homeschoolers who are NOT Christians. It IS very hard to find curriculum that doesn't present the Christian belief system in so many lessons. That was one thing I did like about K12 was that religion was presented in an historic context and you could do with it as you pleased. However, as homeschooling continues to grow, I'm certain there will be more and more options available. "Back in the day", ABEKA was one of the few I could use with my older two and I struggled b/c it was actually written for private Christian schools, so many of the things simply didn't work in a one-on-one situation. Homeschooling has come such a long way since then and I love it when I see "inclusive" groups working together.
Another aside: my DDs were once in an ice skating class made up mostly of Christian kids. A new boy joined who was pagan and I decided to watch the dynamic. Parents basically refused to talk to the mom and watched the kids like a hawk. The kids, on the other hand, took right to him and they always had a great time playing together. I was proud to say that the KIDS behaved in a more Christ-like manner than the parents. I was happy to chat with the mom, she was cool and I actually learned a lot from her about techniques she'd used that worked for my DDs as well.