On a cold and rainy recent Friday night, four jazz musicians jammed before a packed house downtown. The trumpet player, eyes closed, blasted out a solo as some members of the audience hollered and clapped along with the music. But this was no dark bar, and those watching certainly weren’t clutching Scotches or martinis. Rather, this was the chapel of the Bowery Mission, and the men who filled the pews were homeless, and waiting for a bowl of soup and a chance to sleep in a warm bed.

The group of 15 rotating musicians, known as the Music Ministry, performs each week at a number of the city’s homeless shelters, church soup kitchens, and substance abuse treatment centers, including the Bowery Mission, All Angels Church, the Teen Challenge Rehab Center and the New York City Rescue Mission. Led by Uros Markovic, a bornagain Christian drummer who hails from Belgrade and started the ministry in 2000, the musicians share jazz and gospel with the homeless and addicted.

“I’m a drummer and a preacher, too,”Mr. Markovic, 33, said as he set up his drums before the performance. “We pray a bit, and use jazz as a musical expression to share Jesus’s love and mercy with these men who need help and hope.”

Through the years, Mr. Markovic has recruited a number of professional musicians to play alongside him in his evangelical work. Since meeting Mr. Markovic through a mutual friend three years ago at Cleopatra’s Needle on the Upper West Side, Eric Lewis, a professional pianist formerly of the Wynton Marsalis Quartet and Jazz at Lincoln Center, has made time to play with the Music Ministry, even when the piano may be out of tune or his schedule is filled with pieces to practice and films to score.

“I play just as hard for these men as I do for the top producers and music label folks,” he said. “This is the one place where I feel real, and reminds me how real life can be, and that informs my artistry.”

For more than an hour, Messrs. Markovic and Lewis, along with bassist Jansen Cinco and trumpeter Takuya Kuroda, played jazz versions of traditional hymns. Cries of “Hallelujah” and “Praise Jesus!” filled the lofty space. In between pieces, Mr. Markovic addressed the crowd and led the spectators in prayer. In the pews, men in winter coats and wool hats huddled together. Some bounced their heads to the beat, while others leaned on their arms, resting in the welcome respite from the freezing weather outside.

For Mr. Cinco, 24, playing bass at these venues isn’t always easy, since the acoustics are often less then perfect. But he returns because he believes in the power of music and because he wants to give back to the community.

“As a musician, it’s challenging to play here. These guys don’t always want to listen,” he said. “So it’s great for me to push myself and be really honest with the music so they can feel something. It’s a small thing I can do to show some love to the people I share the city with.”

As the performance came to a close, Mr. Markovic invited the audience up to the stage for an altar call, to be “born again.” A man in a leather trench coat strode up, and they knelt together as men in the pews joined hands in prayer. Afterward, they embraced, and the band played “Jesus Saves,” a rousing number that had several of the men dancing in the aisles.

“When you hear music like that, it touches the spirit,” a client of the Bowery Mission Discipleship Institute, a six-month residential recovery program for formerly homeless men, Orrin Johnson, said.

After the music ended and the men had filed out for dinner, the musicians packed up their instruments and put on their coats to leave. Mr. Markovic hopes to take the Music Ministry even further than the shelters it currently frequents, perhaps to prisons like Rikers Island.

“We are looking for funding,” he said, picking up his drum set, “but we will expand. Money is not going to stop us.”