December after December, choirs—big and small, professional and not-so-much—sell out performance venues singing a technically demanding work written in 1741.

In New York City alone this season, there are at least 30 concerts devoted to Handel's "Messiah," and at least 10 that combine the work's Christmas portion with other holiday tunes. Five are at Carnegie Hall, 10 at Lincoln Center, and the rest scattered throughout town at churches, schools and colleges.

This season's "Messiah" menu includes performances by men's and Korean choirs, and orchestras that range from petite to gigantic, complete with expanded percussion and two harps. There are several singalongs, including one at a Park Slope synagogue.

Conductor Michael Conley leads singers in a singalong of Handel's 'Messiah' at Judson Memorial Church in Greenwich Village. Keith Bedford for The Wall Street Journal

Since 1891, the piece has been performed at Carnegie about 350 times. The late conductor Leonard Bernstein's "Messiah" score is the second most-viewed item in the New York Philharmonic's digital archives; Bernstein's score of Mahler's "Symphony No. 9" takes first place.

"It falls into that category of classical pieces that do live up to the hype," said Andrew Manze, who is conducting the New York Philharmonic's five "Messiah" performances.

The work has a lot going for it. It is in English but crosses cultural boundaries, has hummable yet complex tunes and achieved the mark of tradition way before "A Charlie Brown Christmas" or "It's a Wonderful Life" showed up.

"Whatever background people are coming from, it's part of the familiar fabric, for many people, since childhood," said the conductor, organist and "Messiah" frequent-flier Kent Tritle, who is involved in eight performances this month. "It affirms a connection with their past, and for many people with their musical past, if they sang in a chorus in junior high."

"Messiah" also seems strangely backlash-proof, since no one earns much money off the work, he said.

"Backlash happens when you hear something too much and maybe in the wrong context," said Mr. Tritle. "It's hard to sell Mazdas with 'I Know That My Redeemer Liveth.' "

"The Messiah" wasn't always considered so G-rated. The work was the "Jesus Christ Superstar" of its time, because it was considered blasphemous to use Scripture—the text is essentially stitched-together New Testament verses—as entertainment, said Tim Slover, author of "Messiah: The Little-Known Story of Handel's Beloved Oratorio."

To make matters worse, a soloist Handel chose for the original performance, Susannah Cibber, was involved in the most salacious sex scandal of the day, Mr. Slover said. (According to historical accounts, Cibber's husband encouraged her affair for monetary reasons. But once jealousy kicked in, he hid a spy behind the wall during his wife's trysts, taking detailed notes for the trial in which the husband sued the lover for stealing his wife's affections.)

"It was like the Whore of Babylon reciting the Lord's Prayer," said Mr. Slover.

These days, the trick to conducting a good "Messiah" is to view it as a large dramatic work, and not a series of miniatures, said Mr. Tritle. "The key is to understand the overall architecture of the piece from large to small."

At the Philharmonic, Mr. Manze won't worry much about imitating what Handel would have heard, but go for a certain Baroque zest, where each performance is unique.

"You should always be thinking fresh," he said. "That's very much how baroque music was intended to be delivered."

Singers perform in a sing-along of Handel's 'Messiah' at the Judson Memorial Church earlier this month. Keith Bedford for The Wall Street Journal

At a recent "Messiah" singalong at Judson Memorial Church in Greenwich Village, conductor Michael Conley's interpretive approach was of the chilled-out variety.

"If there are little notes, just ignore them," he told his 240 singers, whose bubbling enthusiasm more than compensated for fudged vocal acrobatics.

The singers had their own explanations about the work's popularity. "It's one of the most stirring pieces of classical music," said Joan Patterson, 79 years old, from Brooklyn, who prefers "uplifting" versions to the "stiff and technically perfect."

"I'm an atheist, and I come here for a religious experience," said Ross London, 64, a criminal lawyer from New Jersey.

Others couldn't resist the tug of family. "My mom loves 'Messiah,' so she's eating this up," said Rob Imig, 25, an engineer who lives in the West Village. "It brings the holiday together and makes it official."

"The rest of my family was going, so I had no choice," said Anais Dallett, 10, munching potato chips at intermission. "But it's cool. I like singing."