I know how you feel. I am in the same situation, or at least I was.
I tried to explain my religion to my mother and when I told her that I was Pagan her first response to me was "Oh, my god you joined a biker gang?" Clearly her lack of understanding or knowledge of the religion made it slightly easier to explain and she was a bit more accepting of my religious views and practices. She was also just happy that I at least believed in some form of higher being.
My father on the other hand looked like he wanted to kill me. He was fairly angry and acted like he didn't hear me after I uttered the words "I'm Pagan." Since then we've both avoided the topic of religion.
My point is, if your parents don't want to accept or like your choices in life the chances are that you aren't going to sway them especially if they are dead set against it.
Explain to them your views, if they'll let you, and try to leave it at that. Once they have a better understanding of it they might change their views. If they don't, at the very least you tried to talk with them about it.