Help violating my rights.?

I live at home and am an adult. My parents have opened my mail which is illegal and say that being a Christian is a requirement which is against the first amendment and is very un-American to say the least. I think (and so did the founding fathers) that everyone should be able to make their own chose about religion and have that respected. I would move out but that would not be in my best overall interests at this point. I know it is my parent’s house but I do not think I am being unreasonable.