We could talk about the theory and principle of this matter for days and days, but the simple facts are that you are being supported by your parents and therefore subject to their authority. What they say goes until you and your boyfriend have the means as adults to make your own way.

Until that time, I would suggest that the best course of action is for you and your Master to simply represent yourselves and your case in the most mature way possible (i.e., state how you're feeling but refrain from getting combative when your parents don't happen to agree or accept). If your mother asked about you having sex, and you (even if only for a moment) felt at least comfortable enough to answer her, perhaps there is room to develop conversation there. Let her know this is something you would like her insight on, even if you may not see eye to eye. Perhaps ask her to to talk to you more about her religious views on the subject, flesh them out so to speak. Show her you're interested and that you're at least considering what she and your dad have to say before making your decisions on sex etc.. It's harder for anyone to judge and point fingers when they know the person they are trying to lay guilt on has actually considered their point of view and is still chossing to engage thier life in the way they choose. If you engage her on the topic conversationally, the tension may lessen and you may have an opportunity to ask quesions and show her where you are coming from as well. I find when people (anyone, not just parents) lecture, it is because they also feel they are not being understood and thus go straight for the "I'll tell you what to do because I can and it's easier than trying to explain" tactic.

As for your boyfriend, whether he wants to "face" them or not, I think it's a good idea that he do it. Your parents are right to suspect there is something he is ashamed of if this guy is shying away from contact with them. Being as the driving situation seems complicated, perhaps instead of picking you up to take to his house, he can drive over and spend some time just at your house. I know that'll suck the fun right out of an evening of sex, or it may even cut the evening short if he has to go home early and get to bed, but doing that once every couple of weeks won't hurt anyone and will do a world of good in building respect between the boyfriend and the parents.