UPDATE: After thinking of my parents feelings and the advice from you lovely people, I realized I went about everything wrong and decided to swallow my pride, be the bigger person and apologize. And surprisingly, they took it well. I said "I'm sorry (say that a lot these days) I got snappy with you. I shouldn't have done that. After all, the Bible says children should honor their parents. I was childish and wrong for what I said. I just wanted to be right. I didn't mean any of it." Then my parents embraced me and my father proceeded to say "I shouldn't have called you an apostate. That's serious. I was a lot like you when I was your age, independent. We just need to do what your grandparents did to me, and keep that fault-finding attitude in check."
So, everything is peaceful at the home front again. And even though I really didn't want to, I'm glad our house isn't a war zone anymore. My father and I worked on my car, then he finished it off with "Isn't Jehovah great? Most worldly families can't get past minor conflict." All's well ends well I guess.