Steven Petrow writes the Civilities column for The Post. His twitter handle is @stevenpetrow.

I wear several Duke hats these days, as an alumnus, a director of the alumni association and the uncle of a Duke freshman. I know the school well. But none of my roles prepared me for the tsunami set off last week by evangelist Franklin Graham’s Facebook post calling on the university to reverse its plan to broadcast a Muslim call to prayer this past Friday from the top of Duke Chapel.

I never would have anticipated how this issue would cleave the community at Duke — whose motto, after all, is “eruditio et religio,” or knowledge and religion — and prompt for me a crisis of identities.

At first I felt pride that Duke had taken such a powerfully symbolic step at a time of so much uncertainty, fear and violence in the world. This is the Duke I know and love.

But Graham’s post brought national attention to the campus, much of it ugly. I was stunned not just by the volume of social media comments that followed but also by their vitriol. Many relied on name-calling; others included shadowy threats: “I’m sure in the future,” said one post on Duke’s Facebook page. “Muslim representatives will honor your support for them by killing some innocent Christians some place near your campus.”

Things only got cloudier and rowdier when college officials reversed course Thursday. The turnabout topped home-pages and front pages, and social media again lit up with both sides of the argument.

Posted one individual on the university’s Facebook page: “So ashamed of the Duke Administration bowing to the racists and bigots.” Duncan Murrell, a writer-in-residence at Duke, e-mailed me: “Predictably, the decision to have the Adhan [prayers] called from atop the Duke Chapel brought out the paranoiacs in full cry. Not as predictably, Duke has decided to let these paranoiacs make this decision for our university. I am furious. . . . [N]ow we know that this was an empty gesture made without conviction, abandoned at the first hollering of the bigots.”

Late Thursday, I read that the director of Duke’s Islamic Studies Center said that there’d been “numerous verified instances of credible threats” against the university community (although Duke’s news release on its decision did not mention security as an issue). That was a frightening revelation.

I switched hats, taking off those of an alumnus and journalist, putting on the one I wear as an uncle. I texted my niece asking her to stay away from the chapel on Friday. A call to prayer was still scheduled there, though it was to be unamplified and issued from ground level.

Was I conflicted? Absolutely. Extremists want others to give in to fear, and just look to the recent march in Paris to see the power of people coming together.

With my worries for my niece alleviated, I approached the chapel just before the call to prayer was to begin. A helicopter circled. News cameras stood ready to capture any violence. More than 50 security officers kept an eye out for “nut cases,” as one official put it to me. The crowd, meanwhile, grew from a few dozen to more than 500 in minutes. The call began and, at that moment, my community stood together for religious pluralism and freedom of expression. This is the Duke I love.