Schism,
There is a way to TRAIN your father to be reasonable. My mother was a lot like your dad. Once I was married and said "mom, I don't want to talk about that" she would get enraged and force the issue at hand.
I adopted a technique that worked over a few months time. I would answer the phone, door, whatever... At the first point where she would bring up something objectionable, I would say "Mom, I love you very much, but I don't feel comfortable talking about this, let's change the subject, please." If she pursued the subject (or other subjects that she knew were off-limits) I would say "Mom, I don't consent to this conversation." After that, I would repeat the EXACT SAME PHRASE twice more. If she still pushed the subject, I would hang up/gather My belongings and leave, etc.
This is important because with the first comment you establish that you do not want to discuss this morally, legally, and ethically. With the three reminders, you continue to withhold consent. By not varying the phrase in any way, you give him/her NO REASON to believe that they are allowed to proceed - EVEN if they think of a new approach the topic. You've said NO. Then by ending contact, you show that you are the strong one, and willing to enforce your limits.
It will take many many times to teach your father that you are serious about maintaining your limits. Slowly you will notice that he will stop after the second or third warning... or he will change the subject until later in the conversation. BE VIGILANT! Don't let him find a weakness in your defenses. If he truly wants contact with you, he will begin to respect your limits and you'll notice that even if he mentions an off-limits topic, he'll suddenly change the subject, rather than risk losing contact...
It works, honest.