There is no common ground
Sadly, this is THE core.
I am the most conservative in my family. I have family who range from moderate to liberal.
I am willing to have discussions if they’re willing to be civil. But if you’re screaming at me about my Trump supporter and belittling me in my home, you’re gone. If you are going to criticize my faith, you’re gone, too, whether or not it is discussed as the reason for said political views.
This was a necessary rule for Thanksgiving 2016.
This led to some interesting contradictions. My aunt and I discussed the kids, her kids, healthcare, technology ... and never discussed politics. The cousins who screamed at me on conservatives are evil, haven’t talked to them since. My brother disagrees with me on most politics, but we can talk about family, movies and history.
Those that recognize a civil common space are welcome. Those who have converted to the social justice religion and hate the infidel, including their family, are not.