I agree with kamuzrana and sea-of-roses. you should make a deal with your parents. try it both ways and then decide...
I appreciate your parents conern for you but I definately dont agree with their reasoning behind why you shouldnt live in a dorm. heh, I wonder what your parents will say if your college was to deny you admission becuase of your religion... Its all about the type of personality your roommate has because at the end of the day its going to be about mutual respect.
I spent a month in Italy last summer with aprox. twenty students from my college (for a course) and what mattered was that we all knew that we were individuals responsible for our own actions. Every single one of us as an individual realized that we didnt have to do anything that we didnt approve of...you know? you're your own person.
But yes, having a crazy roommate can be an issue but then again...that crazy person can be anybody eh? (think of that...which is why i'd say...try it both ways. see what works best in the end).
benefits of living at home: good food and familiarity and comforts...

really, food is the best thing about living at home. im sick of college food. its expensive and fattening and doesnt taste good.