My older brother got really extreme ideas about our religion that is ruining our family and I need him to change back to the way he was

My family practices reform Judaism. And but when my brother went to college he got very conservative in a really bad way.

And it made my family really upset and he freaked out at my sister for dating someone who wasn’t Jewish. And doesn’t think people can covert and even of he wanted to. And it was my dads fault for letting her to go to college and I shouldn’t get to go when I can. And he said a lot worse too about my sister being like a betrayer.

My sister won’t even talk to him anymore. And my parents didn’t want him to come home for summer break. And they would argue so much and he’s doing really mean things to me that would completely ruin our family if my parents found out. And people think I should just tell them but he’s was really nice always and still can be and I think maybe he’s brainwashed because he’s completely changed our religion into something it never was to us. I just want him to be like he used to be

Maybe people here know a good way to like change people back if they start getting bad ideas like that..

And if I did tell to my parents I think it would just get a lot worse because then we wouldn’t be there for him anymore. I don’t want to make things