Speech limits on your property
The First Amendment applies only to governments. You are free to banish people from your property if you don’t like what they say, provided the law otherwise allows it. That doesn’t mean it’s always a good idea, though.
A few years ago, some stores posted announcements that they’d banish customers who expressed racist ideas. This was a bad idea, and it’s rare today. Untrained employees would have to eavesdrop on conversations, and they could easily misunderstand what they overheard. And once you start going down that road, is there any reason to stop with just one idea? Banning people for expressing socialist ideas would make as much (or little) sense. Best not to try to police people’s opinions. People can still be kicked out for being disruptive or harassing people, regardless of what opinions motivate them. It’s bad business to 86 customers for their ideas.
In your home, you have more leeway, but courtesy imposes some limits. If someone expressed ideas I strongly objected to, I might explain why I thought they were wrong, or I might say that I don’t want to have that discussion here. If the visitor persisted, I might have to say, “Drop it or take it outside,” and follow through if necessary. Be careful about debating such people. A well-prepared person with lots of memorized arguments can often out-debate a more reasonable person who doesn’t have a stock of comebacks and citations at hand.
I’d object less strongly to abstract ideas than to proposals for violence. Anyone who advocates direct violence except for defensive purposes will be lucky to get a warning from me. Supporting racial pseudo-science in the abstract would annoy me, but I’d be more polite about it.
On the Internet, I can block, mute, or ignore people who say disgusting things. I make frequent use of this option, though I try to remember that letting them see what I say may lead them to better thinking. My own peace of mind has to come first, though.
