My best friend is forbidden to talk to me...?

Well recently, my best friend, who's been so for years, was forbidden to speak to me by her mom because I'm not the same religion as their family. I honestly think this is ridiculous that this has come up all of the sudden and that her measures are being extremist and offensive. Her mom has blocked my number from her phone, spoken to the counselors at school to request we be put in different classes, and told her daughter that if she is caught speaking to me then she'll be in trouble. Is there any way I can speak to her mother in a calm and polite manner about what she's doing without sounding too angry? I really don't want our friendship to end because of something stupid like this. Thanks.