You actually answered your question in the first paragraph. The Parties have become like religions and are supported by the various sects of Christianity. This is especially true of the Republicans who sought out and embraced the Christian Nationalist and Evangelicals to form a guaranteed voting block. But like religion’s history, they tried to take over and found their new leader in Trump, much to the chagrin of the old order Conservatives, who were forced to worship him in order to win elections. But now that moral people have seen the result of not participating and showed up to vote, the Republicans are in a quandary within their Party, just as the Catholics and the Protestants split the Christian church during the reformation. The Democrats have divisions as well, between the old guard and the Progressives. So far, besides Bernie, a true leader has not risen to lead the schism. And overthrowing Trump was a more important goal than finding a new prince (princess). But Hillary’s loss was greatly due to this split in 2016, and it will become more pronounced, I think, in coming elections and primaries, just as the Republicans face thei own split.
I never had any problems being friends with the Republicans in my family (most are), but it’s very hard to remain friends once they joined the Trump cult. How can you make nice with people who believe your Party is run by baby eating Satan worshippers intent on destroying Christianity? Even after we just elected a most pious Catholic to the Presidency? Biden did not acquire his faith as a way to secure votes like his predecessor, and unlike Trump, has suffered great tragedy in his life.
In order to unite, both side have to respect facts and the rules of law. I don’t see that happening anytime soon. And I think we are just getting started on some really rough times for our country.