Let's begin by acknowledging that the answer is not never. We agree that you shouldn't be friends with a neo-Nazi, for example. James Fields used to draw swastikas in school and talk about his love of Hitler. None of his classmates were surprised when he drove his car into a crowd of counter-protesters in Charlottesville in 2017. And yet, surprisingly, "He had friends," one classmate said, "he had people who would chat with him. It wasn't like he was an outcast."[1]
A line of decency exists somewhere between mainstream conservatism and neo-Nazism, and when someone crosses that line, they deserve to be shunned. But where exactly that line is can be hard to identify, and varies from person to person. I myself have Facebook friends who I consider to be very far-right—as compared to me, at least—and I sometimes cringe at supposedly ironic jokes that clearly aren't ironic, or "edgy" memes that go too far. In the past, I've argued vociferously with such people, but I've since found that arguing politics on Facebook, in addition to being unhealthy, is simply not effective.
I suppose we should ask, what makes a "friend"? A friend is someone we enjoy talking to and spending time with—someone with shared interests and experiences. We want our friends to be supportive of us and to accept us for who we are. But at the same time, we need our friends to be honest and tell us when we're wrong, too. And we have this responsibility to them, as well.
Our need to be supportive versus our need to be honest represents a tension at the heart of every friendship—one that becomes more taut the farther apart we are from each other politically. This is why politics can come between friends; it's hard to want our friend to be their best self when they hold political views that we find abhorrent. Political differences—or religious or philosophical differences, for that matter—can only be overcome by our bond over the interests and experiences that we have in common. The stronger that bond, the more resilient the friendship is to political differences.
In the case of "Facebook friends," this bond is usually rather weak. Odds are you don't know the person very well; they can be an old classmate you barely remember, someone you met in a Facebook group, an ex-boyfriend, or a family member (or someone else's family member) who you hardly ever see. In this case, it's straightforward and easy to "unfriend" someone because of their politics, because this isn't a friendship that you valued in the first place.
But when do you "unfriend" a good friend because of objectionable political views? I probably have a higher bar than most—or lower bar, depending how you see it—because I want my views to be challenged. The occasional, friendly argument over politics compels me to develop and sharpen the vocabulary with which I defend my views. And every so often I'm persuaded that I'm wrong, and I change my views accordingly. Thus, occasionally, a friend with adverse opinions can help me grow as a person.
However, this doesn't mean that any adverse opinion should be tolerated. As a general rule, I tend to draw that line of decency on any political views that would violate mine or someone else's human rights. I don't abide dehumanization of groups of people—especially marginalized groups such as trans or other LGBTQ+ folks and/or people of color. I can't imagine any bond of friendship that would be strong enough to withstand avowed racism or transphobia. I would never be friends with James Fields, for instance.
Now, let's get to the question everyone is thinking—does this include Trump supporters? My answer is "not necessarily." I believe it's possible for some people to support Trump and not be racist—they are ignorant, however, in my opinion. To be clear, I think that Trump's calls to "build the wall" and for "law and order" are racially-charged. But not everyone's support for these things is necessarily racist. It may be foolish of me, but I believe that most people have good intentions, and that even if they may be ignorant, they can be educated as long as they aren't hateful people, like Trump. It's important for we leftists to remember this, lest in our zeal for social justice we become an inquisition and end up with no friends at all.
(I would also be remiss if I didn't mention that unacceptable views can certainly occur on the left, too. The title of this article is, to an extent, clickbait. But personally—perhaps because of my own left-leaning political orientation—I don't find these views anywhere near as prevalent on the left as they are on the right. While left-wing radicalization is possible, I believe right-wing radicalization is orders of magnitude worse. There simply isn't the same disdain for human rights or track record of violence on the contemporary left as is found on the right, in my experience.)
So, it's complicated. Friends should support us, but they should also challenge us personally and politically. Politics should be within the bounds of friendly discourse, provided that basic human rights aren't in dispute. Exposure to opposing views is how we grow as people. And where possible, we should assume the best of our friends, not the worst. That is the way to robust and healthy friendships.