My bf's family's religion does not agree with our relationship... help?

I have been dating him for over five months now, and his family is four square Pentecostal, and they only believe in courtship. I am very family oriented, and I don't want our relationship to tear him and his family apart, especially because we can see this going somewhere, and they might be my family as well someday. His family likes me and accepts me as a person, and his older sister went so far as to say that I am perfect for hanging out with his parents. We never hid the fact that we were with each other, but now his parents have decided to step in. We are both graduating and starting college next year. I have no idea how to deal with this situation gracefully. Please help?