Sunday will mark one year since the Tree of Life massacre, the deadliest act of anti-Semitism in American history.

It’s a day to reflect on the lives so brutally taken, and on the need for vigilance in the face of irrational hatred.

For me, the day has special resonance.

The massacre happened in Pittsburgh, my hometown, at the synagogue I grew up attending. My grandparents, Alex and Leona Robinson, helped build the synagogue’s social pavilion, which is dedicated in their memory.

I have particularly fond memories of Cecil Rosenthal, one of the victims.

A gentle giant of a man, Cecil often stood at the front of the synagogue and welcomed members and visitors. He had developmental disabilities, but they didn’t stop him from working and contributing. Like his brother, David Rosenthal, Cecil served as an usher and ran errands to assist the rabbi. He radiated goodness.

Judah Samet, who was likely spared because he was running late to services that morning, is a family friend. A former IDF paratrooper and Holocaust survivor, Samet, 81, tells me he locked eyes with the shooter and was later able to provide details to the FBI.

In a rare moment of national unity during the State of the Union Address in February, President Trump honored Samet, and Congress sang “Happy Birthday” to him in front of millions.

Samet urges vigilance against anti-Semitism, an ancient virus that today infects extremist elements on America’s left and far right. Using the Yiddish word for “crazy” he tells me, “There are meshuggenehs on both sides.”

Samet adds, “Groupthink drives this country today, and that’s a problem.”

Experts warn that vigilance means realizing anti-Semitism does not have one face, one political party, one ideology.

And it means being proactive about security.

“We should welcome the stranger, but we need to be sure the stranger isn’t coming to harm us,” says Michael Masters, national director and CEO of the Secure Community Network, the official security organization for the Jewish community in North America.

Masters stresses the need for Jewish institutions to be proactive via increased security measures, often including armed guards.

The call to action should not fall on deaf ears here in New York, where anti-Semitism is on the rise.

According to the NYPD, the city recorded 323 hate crimes from January through Oct. 6, up 33% over the same time in 2018 — with anti-Semitic incidents accounting for the majority of those incidents.

As we fortify ourselves against this threat, we will continue to remember the fallen and the high ideals for which many of them strove.

Dr. Joel Weinberg worked in the same hospital and was a close friend of Dr. Jerry Rabinowitz, the family physician who reportedly died rushing toward the sounds of gunfire to try to help the wounded that day. Weinberg believes Rabinowitz’s instincts as a doctor took over in the final moments of his life.

“To run to try to help somebody was totally in character” for Rabinowitz, Weinberg notes.

Judaism teaches that to die while actively serving God is the highest elevation of a life spent on earth.

On this solemn anniversary, let us honor and remember all the victims: Joyce Feinberg, Dr. Richard Gottfried, Rose Mallinger, Dr. Jerry Rabinowitz, Cecil Rosenthal, David Rosenthal, Bernice Simon, Sylvan Simon, Daniel Stein, Melvin Wax, Irving Younger.

These individuals, who died simply for observing their faith, will be enshrined in the collective memory of Jewish Americans, and of world Jewry, for eternity.

As Americans, they were also citizens of a nation founded on religious freedom.

Let their memories be a blessing then, not just to Jewish Americans, but to all Americans.

Murdered while worshipping in Pennsylvania, one of America’s first states and founded by Quakers seeking refuge from religious persecution, their legacies will remind us to treasure the freedom of worship and belief that is our birthright as Americans. And of some of the highest qualities to which a human being can aspire: love, kindness and selflessness.

Twitter: @HE_Robinson