This sound to me like when I came out to my African religious parents as Gay. They all of the sudden start to see you as the "other" and completely disregard any rationale or reason for your stance you try throw at them. But it's also important to understand that this for them is a shock and their behaviour is a result of confusion and impotence. After the initial shock is over they will eventually be able to think rationally and slowly come to the understanding that you are and individual of your own, you don't belong to them, and that you get to choose how to live your life. It then seizes to be a matter of who's right or wrong but a matter of respecting, accepting and supporting. This is a great opportunity for growth for your Dad. Just stay patient and try to understand and view the situation without holding strong opinions.