If you live with them it could be tricky but let them know you will not be talking politics or any kind of emotionally charged topic with them going forward. Lets keep it light and stick to the things we agree on and leave everything else at the door. Avoid talking about them or saying you or sounding accusatory to minimize defensiveness, just let them know these topics and conversations are not how you want to use your time and energy and thinking anymore.
If they start trying to drag you into a forbidden topic, simply let them know you are heading off to do something since you dont have anything to add or contribute to topics that you are uncomfortable with like you mentioned to them before.
Start with this and let us know if they bite. I’ve got some other ideas but start with this and see how it goes. At the end of the day, engaging in these kinds of discussions over and rehashed constantly is damaging and pointless so the key is transcending them by not participating in them or feeding the wrong wolf. Be polite and respectful but also assertive that you will not be dealing with these topics any longer
Ya just let him know you’re not spending your time and mental energy on that stuff. Stop talking to him on the phone or let him know that as soon as things are falling off course into that stuff, you gotta go and take a break from him for a few weeks.
Eventually he will get the message but if its still a problem after that, might need to go no contact to demonstrate you’re serious