We don't disown people in my family. I could be a serial killing, psycho and they'd still love me (although I would have to put up with endless lectures about how wrong it is to kill people and stupid jokes about hiding the knives).
My family are Christains but they're pretty tolerant and they understand that it's all the same God. from their point of view a Muslim is better than an athiest although they would be ok with that too - like I said however much they disapprove of my choices they would never disown me.