Now, the crowd has aged, with fewer young neighbors in attendance. Campbell attributes that to what he calls the city's "mobile generation," who are comfortable shopping around for churches and don't mind traveling to pray.
"The older generation's loyalty was taken for granted," he said. "Neighborhood churches cannot rely on that anymore, and have to find ways to woo younger people."
Although the church is well-attended, with a body of about 1,700 parishioners, Campbell misses the early days of his ministry, when he preached to crowds that exceeded 2,000.
Where we worship: Mt. Carmel's members gather for services in an expansive church on Race Street near 58th, a venue that's a far cry from the basement where the historic parish first gathered in the late 1880s.
Years of growth and expansion spearheaded by Campbell during the early years of his ministry saw the addition of a parking lot and some nearby buildings to the church's campus.
"Whenever the notion of relocating to a bigger location was suggested, we always weighed it carefully," Campbell said.
"But leaving our community would convey the image of running away from or abandoning something we are an integral part of."
How we worship: The church offers two services on Sunday mornings: an "Hour of Power" at 7:30 that packs contemporary music and more lively worship into a shorter-than-normal session, and a more traditional, reserved service at 10.
The earlier session addresses the need to attract younger parishioners - something all city churches, regardless of faith, must strive for, Campbell said.
"We had to find a way to make ourselves attractive to them without throwing the baby out with the bathwater," he said. "I think we've found a happy medium."
What we believe: As the name implies, baptism is central to Baptists, and takes place when the churchgoer is grown, not an infant. "The person being accepted into our faith has to be of an age where he or she can understand and confess their faith in Jesus," Campbell said. "Babies are simply unable to do that."
Like all Baptist congregations, Mt. Carmel is independent, meaning that it doesn't answer to a regional authority. "The highest court of appeals for local congregations is the congregation itself," Campbell said. "We have the final ecclesiastical say of what happens in our ranks and in our ministry."
What we're known for: Mt. Carmel has some prominent parishioners, including Mayor Nutter, who gave an impassioned speech at the church about ending youth violence in the wake of the city's flash-mob outbreak in 2011.
Other politicos known to warm the church's pews include state Sens. Vincent Hughes and Anthony Hardy Williams. NBC10 news anchor Renee Chenault and U.S. Rep. Chaka Fattah were married here in 2001.
"As pastor, I've tried to make us politically connected," Campbell said. "Political issues impact those who sustain and support the people who need the church's services."
Good works: In addition to operating a food pantry and clothing-donation center, Mt. Carmel runs the adjacent Mt. Carmel Gardens, a housing development intended for low- and middle-income tenants.
Moving mountains: About 15 years ago, Campbell took up the then-fledgling campaign to allow women to be ordained as Baptist deacons.
It was a tough fight, he said, but he had a powerful ally in former U.S. Rep. William H. Gray III. The Philly political giant and minister, who died in July, asked Campbell to preach the sermon ordaining the first female deacons at Bright Hope Baptist Church.
"We were trendsetters, leading to something that would eventually become standard, but still, to this day, I get the occasional backlash from people who don't accept the notion," Campbell said.