BlackWolf, you handled the study very well. I think it is good that you are trying to be honest, rational, firm, but kind with your Dad. This is what I did with my parents too when I was your age as well as into my young adulthood. It has been successful in me being able to maintain my relationship with them even though, at times, it has been strained and difficult.
I think it is also good that you bring some relevant Scientific information to the studies. Teachers learn from students almost as much as students learn from teachers. It is a reciprocal relationship (as all relationships should be). You have an opportunity here to give your Dad some knowledge he might otherwise not get studying with someone else he's trying to recruit.
It is possible your Dad is bipolar. I find a lot of people in this religion have these kinds of issues. My parents became like this. I tried to remain calm, rational, and kind when they became angry, delusional, and mean. "Emotions Down, Productivity Up." This is a phrase Monty Roberts uses when dealing with horses... and humans. I have used this and I find that it works.
I used to have an Instagram account but I think they deleted it after they decided to not let PC users upload images anymore. I presently don't have 'data' on my SmartPhone as it is an extra cost and I wouldn't use it very much anyway.