Pushing past the chestnut carts, day-trippers, and Salvation Army bell-ringers that clog Fifth Avenue the week before Christmas, I climb the steps of St. Thomas Church, the imposing gothic pile on the corner of 53rd Street that abuts the Museum of Modern Art. Inside, the St. Thomas Boys Choir is standing on the altar in seasonal red vestments, singing Benjamin Britten’s “A Ceremony of Carols” as part of their annual holiday concert. Led by their director John Scott—formerly the organist and director of music at St. Paul’s Cathedral in London—and accompanied by harpist Anna Reinersman, the boys’ treble voices soar in the high stone nave, clear and resonant all the way to my seat in the organ loft. For an hour or so, I am transported far from the clamor outside.

A few days later, I’m downtown at St. Paul’s Chapel at Trinity Wall Street for the Sunday night service known as Compline, sung by the Choir of Trinity Wall Street under their director, Julian Wachner. With the nave lit only by candles, the choir sings a haunting mix of plainchant and improvised music, putting a modern spin on the ancient monastic service.

Compline is just one of several musical events presented by Trinity Wall Street each week: there are lunchtime concerts devoted to Bach’s cantatas on Mondays, plus organ music every Wednesday and chamber and contemporary music on Thursdays, along with regular performances of operas and other large-scale works featuring Trinity’s in-house orchestra, NOVUS NY. Almost all are free.

It is irrefutable that sacred music lies at the center of the Western classical music tradition. From Gregorian chant to Bach, Britten, and beyond, more music has been written for the church than for any other institution. But in a city with a surfeit of world-class performing arts institutions, music lovers tend to overlook the day-to-day musical offerings at places like St. Thomas or Trinity, perhaps put off by their religious underpinnings.

Sacred music has had an outsized influence on one surprising corner of the New York musical world: the post-classical scene found at places like Le Poisson Rouge or heard on the label New Amsterdam Records. Much of this is because churches offer a flexible schedule and a steady source of income for fledgling freelance musicians, as they have for centuries. But after speaking with several prominent composers, all in their early 30s, it’s clear that while singing in church may be a day job, it’s also an inspiration for their own music.

Composer and violinist Caleb Burhans spent nearly 20 years in church choirs, including seven years as a countertenor at Trinity. “Choral music is central to who I am,” Caleb says, “It informs everything I do. There’s something about the visceral experience of singing close harmonies with others that I really like.”

Caleb, who considers himself agnostic, admits to being ambivalent when it comes to the religious nature of this music. A case in point is his debut album, Evensong (Cantaloupe Music), with its ambient and post-rock settings of traditional Anglican verses.

I guess you could say I’m on a personal quest to reconcile with Christianity through my music. Subconsciously, I’ll tweak a harmony to be subversive, or will tip my hat to the past by quoting a motif or cadence from some 16th-century hymn or motet.

Another composer strongly influenced by sacred music is Nico Muhly, whose earliest performing experience was as a boy soprano at Grace Episcopal Church in Providence, Rhode Island. In his 2005 Guardian essay “Choral Sex,” Nico said that after his voice changed, he carried his affinities for the Anglican choral tradition­—its localized repetitions, small gestures, and overall restraint—over to his own music.

“It’s become a cantus firmus through everything I do,” he said in an interview with the Metropolitan Opera last year, “not just musically, but also as a sort of philosophy of how to make music and think of yourself as a composer.”

In addition to writing large scale works like his opera Two Boys, staged earlier this season by the Met, Nico has composed a great deal of choral music, much of it for John Scott and the St. Thomas Choir. “With sacred music,” he says, “your obligation is to the bigger narrative of the fundamental story of the church. But because everybody knows the story, the composer’s job is one of shading and re-telling.”

Even for non-composers, the daily rigor of singing in a church choir can be beneficial. Soprano Mellissa Hughes, one of new music’s most sought-after and dynamic singers, says that her day job as a member of the Trinity Choir has been invaluable in honing sight-reading chops and other technical skills.

“I wouldn’t be where I am today if I hadn’t sung in choirs,” she says. “There are these little tricks you learn that come from knowing your instrument and working in a group setting.”

Bora Yoon is an experimental composer and performer who creates surreal soundscapes by blending electronics and found objects with her own voice. Bora says that while her membership in the Voices of Ascencion choir has turned some heads among her avant-garde peers, it’s had a profound influence on how she thinks about performance, and music in general:

As a singer and composer, I get influenced just by having to sing through all of this varied repertoire week after week that I wouldn’t normally be exposed to. I have access to this great wealth of knowledge about how timbre works, how spatialization of sound works, what makes one period sound different from another.

According to Trinity's Wachner, this kind of cross-influence works both ways.

My administrators think I’m insane, but I don’t have any regulation on attendance. First of all, it allows the singers to pay their rent, but more importantly it keeps them artistically satisfied, so that when they come back to Trinity from singing in these other groups, they come back with these experiences that increase what we do.

One of these groups is the Grammy award-winning a cappella octet Roomful of Teeth, half of whom come from the Trinity Choir (a fifth member sings with St. Thomas). The group incorporates folk-based vocal practices from all over the world, including yodeling, Korean P’ansori, and Tuvan throat singing.

“It seemed like a given to me,” says their director Brad Wells, “that composers would enjoy writing for the voice in dramatically different gears from bel canto, to throat singing, to all of these different kinds of techniques.”

One of Roomful of Teeth’s members, Caroline Shaw, used many of these techniques in her “Partita for 8 Voices,” which won last year’s Pulitzer Prize for music. Caroline, who sang in the choir of Christ Church New Haven before moving to New York in 2008, says she didn’t initially set out to write something so substantial: “I’m not sure what the impetus for it was, other than wanting a certain kind of clarity.”

As a result, “Partita” has a bold, unadorned sound that is both vividly fresh and strangely familiar—it catches you off-guard. “When we first performed “Passacaglia” (the first movement) in 2009,” Wells recalls, “there was a real power to it. People were leaning forward in their chairs; they couldn’t help but cheer right in the middle of it.”

On a snowy Saturday in December, I trekked to Brooklyn College’s Walt Whitman Hall for a holiday concert by the Grammy Award-winning Brooklyn Youth Chorus (B.Y.C.), made up of kids aged 11 to 18. After sing-alongs of “Jingle Bells” and “Rudolph the Red Nosed Reindeer,” the B.Y.C. performed Shaw’s “Its Motion Keeps,” a mesmerizing homage to “A Ceremony of Carols,” with overlapping, antiphonal sounds marked by dissonance and decay. “Its Motion Keeps” was commissioned by the B.Y.C. last year as part of their New Voices Commissioning Project, which has yielded more than two dozen works to date.

“The existing body of music for treble-voice youth chorus is somewhat limited,” says B.Y.C. Founder and Director Dianne Berkun-Menaker.

Commissioning music has made it possible to find and express our own unique voice. The range of composers that B.Y.C. has worked with, from John Adams to Shaw, has provided the chorus with musical challenges on every level—from vocal technique to complex harmonies and polyrhythms.

The following week, I went to hear the Sunday night meditation at the Church of the Ascension, a quiet, reflective service with a cappella music sung by Bora from the organ loft. The music all sounded like it came from the same period, though I couldn’t tell which. When I saw her afterwards, Bora said the first selection was by the medieval abbess Hildegard von Bingen (1098 – 1179), but the others were by David Lang and Meredith Monk, both living New York composers.

“We’re revisiting the same side of the record, just several grooves in,” she told me.

Hildegard’s music is nearly 1,000 years old, and it still carries the resonance it does because it has a universal nature that will never outdate itself. Classic and romantic periods are very declarative and presentational, whereas medieval and postmodern music both have an inward quality that has a glow to it, that’s very clear and transportive. It’s all cyclical.

Wachner hears a similar thread. “The choral tradition is based primarily on a modal system,” he says.

It’s 16th century white note minstrel notation that’s based on a fixed set of constrained pitches. Which is also where contemporary music comes from. And so, I think today’s minimalism and mystic minimalism has been a return to medievalism. There’s a real affinity between those two worlds.

Beyond the technical similarities between Renaissance and contemporary music, I wondered if the daily practice of singing sacred choral music also affected these young musicians in a metaphysical way. Almost everyone I spoke with could recall at least one instance where they were caught off guard by the emotional resonance of singing in church, be it hearing the reverberation of their voice or the spiritual content of the text. Tempting as it is to define such experiences as “Road to Damascus” moments, Wachner says that’s missing the point.

“All music is church,” he says. “All music is spirituality, whether it’s specific or whether it’s a reference.”

On a recent Sunday afternoon, I made my way back to St. Thomas for Evensong, the daily choral service that has been sung in some form since the Middle Ages. Although elements of the service change depending on the day, the “Magnificat”—Mary’s song of praise when she realizes she is the fulfillment of the Old Testament prophecies—has been sung at every Evensong for more than 1,500 years. Countless composers have set this text—on this day the music was by Francis Jackson, the former organist and director of music at York Minster Cathedral, still active at the age of 96. As the voices of the men and boys soared over the rumbling bass line of the organ, one verse resonated beyond the others:

He hath filled the hungry with good things,
and the rich he hath sent away empty.

As I walked out onto Fifth Avenue, I thought about how classical music left so much of the past behind and wandered the desert of serialism for the better part of the 20th century, leaving many hungry for the familiar joys of tonality. In the early years of this century, contemporary musicians are reminding us that no matter what church we belong to, music can bring us all closer to the divine.