Coming out is always tough.
My girlfriends mum is a lesbian, and she *still* didn't take her own kids queerness too well. I think she wanted her kids to have a bit of an easier life than hers, and wasn't really on top of the idea that things are easier now than they were when she was devorcing her second husband and finally coming out.
My mum was heavily religious, and she pinned me for gay before I was certain myself. Me and my best friend were both obviously queer - he was a 'sissy', and I was a 'tomboy', and so we were spammed with books about how The Gay would kill us and make us miserable from about 12 years old on. My mum did eventually come around to the concept, but since then we have lost touch for other reasons. (My choice, not hers).
So I would advocate patience. And possibly tricking them into watching But I'm a Cheerleader for the lols.
The sound like good people, who love you, so I'm sure they'll come around. Especially if you find an especially charming partner. (Nice partners always help convince parents of their childs future happiness, regardless of that partners gender).
If you can convince them, PFLAG have tons of great resources.
Also I've heard good things about this book, though I haven't read it myself:
http://www.amazon.com/Straight-Parents-Gay-Children-Families/dp/1560254521Also if they are christians of a pentecostal bent, look up Anthony Venn Brown, he's an australian pastor who is an out gay man.