Brother-in-law views my gift as satanic

So for context I 30(f) have a sister 24(f) she got married a few years ago to her current husband 28(m). I say current because I'm not the biggest fan of him. But whatever makes my sister happy I'll support her. After they got married she moved with him to a different state and live with his family. I saw no issue as this is her choice while they save for a house and try to be financially responsible. However. I hear from my sister atleast once a week about how his family treats her. Or how eve her husband treats her. His mom always comes first. She needs something husband will drop everything for her. My sister asks for help and he could care less. Mom in law is always around and needing him. Will walk into their bedroom unannounced and wake them or say she needs something (she is not disabled by any means, and her husband as well as another son are around) flash forward to this week i got my sister a gift. A bracelet with a moon on it, she loves stuff like this so do I so i never viewd it as an issue. When my sister came home with it to show her husband he claimed it wasn't very "Christian like" jewelry. It seemed witchy and satanic. (They are extremely devout to their religion) it was a moonstone with a blue moon phase on it. It was beautiful. Her husband threw a fit and called his mom to come look and they ganged up on my sister to throw it away. It goes againt christian values. If I got her tarot cards I could see the uproar but its a bracelet of a moon. She is upset and now his mother is practically going through their room looking for things she deems satanic. Same woman who thinks Harry potter books are satanic if it has magic or dragons. It is bad and must be thrown away. In my opinion I want to go strangle the family and get my sister far away. But shes upset and my instinct says to go get her and kick some ass on the way. My sister asked me not to and I said I wouldn't help her escape unless she wanted to. But I do want to go off in her husband and plan to. Am I wrong for wanting to stand up for my little sister?