Susan Shapiro is the author of "Lighting Up: How I Stopped Smoking, Drinking, and Everything Else I Loved in Life Except Sex" and co-author of "Unhooked: How to Quit Anything."

(Reuters/Regis Duvignau/Files)

As a journalism professor, I had made a decision to be politically neutral on social media. Then an Egyptian-born former student tweeted about “Israeli war criminals” with a swastika next to the Israeli flag.

I’m a Jew with many beloved relatives in the Holy Land, and I was angry. I wanted to avoid the instant gratification of a sharp response; this issue wouldn’t be solved by broadcasting quips or soundbites to my 10,000 followers and fans, many of whom had taken my classes. But the next day, a Balkan Facebook friend posted a call to “prosecute Israel to stop the Zionist genocide.” My blood pressure spiked. I de-friended him and un-followed my Egyptian student, relieved to blow them both off my news feed.

I rationalized my choice. In the past 21 years, I’d helped people of all backgrounds publish rallying cries against the racism, homophobia and xenophobia they’d experienced. I’d coauthored a book with my Bosnian physical therapist, writing about the ethnic cleansing campaign against Muslims in the 1992 Balkan War. He fixed my damaged spine while I helped him document his childhood trauma. But when Balkanites who’d befriended me traded anti-Israel tirades on Instagram, Twitter and Tumblr, I didn’t want to listen. I wanted to squash it.

I wasn’t alone in blocking the barrage of crude opinions on social media. Hate speech during the Gaza War last summer prompted a Jewish friend to deactivate her Facebook account altogether. Sickened by racist sentiments justifying police brutality in Ferguson, Mo.,  an African American student of mine zapped away the bigots from her lists and contacts, declaring on her Twitter bio: “If discussions on racism make you uncomfortable, avoid everything I write.” Whenever race, religion and violence intersect in the news, the instinct is to excise the other side from your screen.

But the idea of creating an echo chamber of only supportive standpoints is a troubling one. I’d eliminated two people who’d posted comments I’d abhorred, erasing them from sight while perhaps exacerbating the underlying dilemma. These weren’t anonymous Internet trolls or strangers; they were humans I knew and liked in my classroom.

I teach writing part-time at Manhattan’s New School for Social Engagement, founded as a University in Exile in 1933, a haven for scholars fleeing Nazi Germany. After publishing a book condemning prejudice against Bosnian Muslims, I could not cower from defending my own tribe.

When a Syrian American pupil posted “Prosecute Zionist Occupiers” with pictures of Arabs killed by Jews, I let myself be pulled in. In a private message, I wrote, “This last war started when three Israeli teens were murdered and 1,000 missiles were fired at us,” and I repeated President Obama’s remark that “Israel has a right to defend itself against what I consider inexcusable attacks from Hamas.” A Turkish protégée posted a flier about Israel’s “decades-long tyranny of the Palestinians.” I e-mailed him directly, asking “What would you do if your home was attacked by weapons, and your children were kidnapped and killed? Spreading anti-Semitism won’t help anybody.”

“Disagreeing with Israel doesn’t make me anti-Semitic!” he shot back.

It felt messy and uncomfortable. But I forwarded him an Atlantic analysis of how the so-called powerful Jewish lobby was dwarfed by 54 Muslim-majority states in the U.N. The article explained that Internet rage illuminated “open, unabashed expression of vitriolic Jew-hatred,” a reminder that much of the world “is not opposed to Israel because of its settlement policy, but because it is a Jewish country.”

He returned with a Huffington Post piece by a Pakistani Canadian doctor. I was surprised to see it was an olive branch. If you support democracy and a two-state solution, the doctor said, you could be anti-Hamas, pro-Israel and pro-Palestine. It hadn’t occurred to me before that I could simultaneously hold all three views. In our battle of links, we were on the same page — for at least one article.

Erasing voices you don’t agree with on social media, even when their words cut deeply, might feel freeing. But after the events in Paris, it’s almost cowardly. Now, when someone posts something anti-Semitic to social media, I reply with photos of a Muslim woman holding a sign that reads “Je suis Juif” and Jews and Muslims refusing to be enemies. So far they’ve garnered many likes, shares and favorites. Using more tact and less extreme rhetoric, social media can be our bridge, not our blockade.