AITA for offending my boyfriend's trans sister?

So I (20f) and my boyfriend (23m) have been dating for a year and a half. A couple months into our relationship his (then brother) came out as a trans woman. They were really close, and it was a huge surprise for my boyfriend.Fast forward more than a year, and his sister has changed so much. She's often really toxic, and is convinced that my boyfriend is also a trans woman, because he's always been a sensitive guy. This bothers my boyfriend to no end, but he can't argue because she accuses people of transphobia when they push back against what she says.She also has a really rocky relationship with her parents, because, to be completely honest, they really weren't as accepting as they should have been. After she changed her name, my boyfriend's mom was like "You'll always be [dead name] to me." They're working on it though, and slowly but surely the family is understanding each other and healing.So this is where I come in. When I was visiting his family, I started talking about my religious beliefs. This was a huge mistake, because discussing religion at your boyfriend's house should be an obvious no. I said that I thought God was a woman, because I felt that making God a man took the creative power, something that is very female in nature due to biology, and turned it into something that males possessed, and women became mere recipients of this power. I said that the female reproductive structure was a metaphor for a more universal creative arch.In case you're wondering, yes I am like a weird hippie-witch. I don't shave my legs, I have really long hair, I love animals, and spend a lot of time in nature and doing art. I had a rough childhood, and I find great solace in my spirituality and embracing of natural femininity as a source of power rather than weakness.Except this made my boyfriend's sister super angry. She didn't say anything to my face, but went on a rant on twitter about me. I didn't understand what I did wrong, and when my boyfriend talked to her, it turns out she found the idea that God was a woman due to the creative force transphobic because it conflates femaleness with biology, and because she can't have kids, and isn't biologically female, she feels hurt and left out of womanhood.When I talked about my religious beliefs I honestly wasn't thinking about trans people or about her, and I never meant to make it seem like I didn't accept her as a woman. I wrote two letters of apology to her, and she hasn't responded. My boyfriend's relationship with her has suffered, partially due to this and partially due to her insistence that he's secretly a woman.I feel really bad about what happened but also the occasional spurt of anger towards her. My boyfriend insists that i did nothing wrong, but I don't know. AITA? via /r/AmItheAsshole https://ift.tt/2SbNhvC