"It's not just a good thing to be involved," he said of community service. "It's a requirement."
Bernstein started the Philadelphia area's King Day of Service in 1995 with 1,000 volunteers - mostly Philadelphia schoolchildren and Americorps volunteers.
It has since spread to cities around the country, and this year's projected turnout in Southeastern Pennsylvania and South Jersey - more than 85,000 - would be the largest in history.
Last week, Bernstein's efforts won him recognition from President Obama, who honored him as one of eight White House Champions for Change for embodying King's legacy.
Harris Wofford, the former Democratic senator from Pennsylvania and a leader in the civil-rights movement, credits Bernstein, a former aide in the 1990s, as the first person who thought Martin Luther King Day "should be a day on rather than a day off."
After Wofford, who led the charge for the law that made King's birthday a national day of service in 1994, lost his Senate seat to Rick Santorum that year, Bernstein began working to become, as Wofford put it, the "foremost driver of that idea on a large community scale."
So how did a white Jew from northwest Philadelphia become the best-known champion of a day devoted to remembering King?
"It's not always been . . . welcome by everyone," the 54-year-old Bernstein admits. "But it makes perfect sense to me."
Bernstein attributes his interest in public service to a 10th-grade trip he made with classmates from Abington Friends School to Scranton to help clean up after Hurricane Agnes in 1972, at the time the costliest hurricane to hit the United States.
We were "literally knee-deep in mud in someone's living room," he remembers.
What stuck with him, he said, is how people from different backgrounds came together to help flood victims.
"We collectively responded," he said.
As for using King's holiday as the springboard for his efforts to promote volunteerism, Bernstein said the African American community didn't have "exclusive ownership" over a man who fought to advance the cause of equality.
He had his skeptics. Philadelphia civil-rights attorney Michael Coard used to count himself among those suspicious of Bernstein, whom he had known casually for years because of his appearances on Mary Mason's popular African American talk radio show on WWDB.
"I'm like, 'Why is this white guy dealing with issues pertaining to black folk? Is he running for office? What's his agenda?' "
But Coard said he was "blown away" when he discovered that Bernstein was working to restore Eden Cemetery in Collingdale in Delaware County, the nation's first public black cemetery, which holds the remains of such African American luminaries as singer Marian Anderson and early civil-rights leader Octavius Catto.
Bernstein was working to clean up the cemetery - which had been the target of vandalism and racist graffiti - "on his hands and knees," Coard said.
And most important, he was doing it with "no cameras, no media attention. It was just that sincerity," Coard added.
That sincerity and persistence mean that Bernstein usually gets his way, said Tamara LaClair, the Girard College admissions director who serves as liaison with Bernstein's organization, Global Citizen.
Bernstein asked the college to participate in the King Day of Service three years ago, after it hired a black female president - a first on two fronts for a school that famously held out for 14 years as activists pushed the school, which educates children from poor families, to finally admit black students in 1968.
When Bernstein made his request, LaClair said, the college expected that he would want the use of one building for service projects.
Before the administration knew it, Girard College was serving as regional headquarters.
"As much as you want to say no, you can't," LaClair said.
These days, Bernstein sees his role as a facilitator, keeping the King engine of volunteerism running smoothly.
He focuses on securing funding for the event, raising about $400,000 this year.
Global Citizen - a limited-liability company with four employees that operates under the auspices of the Urban Affairs Coalition - provides a central clearinghouse to match interested organizations and projects with potential volunteers.
But Bernstein's seemingly boundless energy means that he is not planning to stop there.
His latest push is to persuade the Philadelphia School District to reincorporate service opportunities into its curriculum, which he thinks could provide meaning for students and help lower violence and dropout rates.
Former Superintendent David Hornbeck championed so-called "service learning" opportunities, which the district has since de-emphasized.
Said Bernstein: "Dr. King is one of the greatest examples of an active citizen, and service learning really teaches and instills in a young person the responsibilities of citizenship."
Contact staff writer Anthony Campisi at 215-854-5015, firstname.lastname@example.org, or @campisia on Twitter.