The key to having a civilized conversation about politics or religion or any controversial subject is to not go into the conversation with the goal of convincing the other side you are right
Fact is, those people you dread talking to almost always think they are completely right and everyone else who doesn't think like they do are completely wrong. And you're no different. So their goal is to convince you. To win the argument.
The technique most of them use is called aggressive assertion where they aggressively assert their "position". This is called a positional argument. Positional arguments rarely succeed because if the other side doesn't believe in their position, all the aggressive assertion of all the facts and beliefs they have won't convince you. You have to remember that they came to these beliefs from a lifetime of experiences and thoughts based on a strong confirmation bias.
So come back around to how you can have a conversation with this type of person.
Step #1. As I said before, change your goal from "winning the argument" to just having a conversation. Remember, what you were dreading was spending time with tis person because you know they just want to argue. You probably wouldn't be at Thanksgiving dinner with them if they are not someone you'd care to get to know better. So your goal is to have an enjoyable conversation and get to know someone better.
Step #2. Instead of ramming your views down their throat, start by trying to find common ground. Most likely, you can find common ground in what you both value.
Step #3. Once you find out what values you have in common, (I call that the "what" you both care about, then your next question is to ask them why they believe what they believe. Your goal at this point is to really listen with an intent to understand why they believe what they do vs you jumping in and telling them why they are wrong.
Step #4. Once you have established that you both have common values, and that you are disagreeing on beliefs, after you have given them the time in step 3 to share their beliefs, and you have listened with the intent to understand and empathize, then your response is a technique called "assertive inquiry".
An example of that response is, "I've heard what you had to say about why you believe the way you do. I can now see why you feel the way you do. I have a different belief that I think is worth hearing.".
Ask them if they would like to hear it. They will most likely say yes. Then you now have a chance to communicate your beliefs. You may want to remind them that you're not trying to convince them they are wrong, you are simply stating your beliefs. Now you need to know they will most likely cut you off and jump in and start aggressive assertion again, it's the only way they know how to have these types of conversations.
Politely remind them of the things you have already talked about (a) your common values (b) You listened to their beliefs patiently and understand and empathize with them, and now it's your turn for them to listen and empathize with your beliefs. At this point it is really hard for someone to deny you the opportunity to talk.
But, if they do, then let them come back to asserting their beliefs, and when they are finished try to repeat step 4 again. If they still don't give you the opportunity to be heard, then it's probably time to go talk to someone else. You'll at least have the comfort in knowing that you know a little more about this person's values and beliefs and they know little about yours. That always puts you in a stronger position in the next conversation.
