How do I make her dad like me?

This girls dad may hate me with a burning pion and I get worried when I don't see my her online. I think he is not letting her talk with me. When he is going to be outside the school she always meets me in the exit hall instead of hanging out with me when I leave, because he is out there. She seems really sad about this and we used to IM - flirt - for hours before he got like this. I first thought of this when he stopped letting her using the phone and got pissed when I called her and did not know. He raves that I am some type of delinquent who will use and abuse his daughter when he has not met me is the context of her boyfriend. We are both fairly young, me a sopre and she a freshman, but I knew her for a while before then and promised myself when we were younger that she would be the girl I married. She is a devout christian something I support and admire, even if I do not subscribe to that one belief, so she does not like to disobey her father, except when it comes to me. She always finds a way to cirvent him which I admire but I am just worried he will kill what we have. How do I get to him?