I'm also in this situation. I am divorced, so my kids are learning Christian principles from their dad and his side of the family (especially my pushy ex-MIL). There is nothing I can do about it. For a long time, my young children were very upset that I didn't believe in Jesus because I was going to hell. They were TERRIFIED on my behalf, because of my ex-family. No matter what I said about people having different beliefs, they were SURE MIL was right about everything. I felt so bad about how my children were feeling, and furious with my ex-family. And there was nothing I could do, because these people are like that on purpose. So I tried to push away feeling upset and keep teaching my children about different beliefs. The library has a handful of children's books about different religions - Hinduism, Buddhism, Judaism, Taoism, Islam, etc., so I kept checking them out and reading to them. Rather than trying to erase my children's knowledge, I had to add on to it. Eventually I came up with a good philosophy in a phrase: "God has many faces and many names." I like watching belly dance videos on YouTube, and I stumbled upon a religious dance from India. It was a woman honoring one of the Hindu gods, and it was beautiful. My younger son was watching with me and asked some questions. I could tell him that the statue was a statue of what that woman thought God might look like. I said this is how people pray in India. Look how she uses her hands and face to pray to God. My son got a huge smile on his face, because I think it all finally clicked for him.