In case you head to St. Gabriel Catholic Church on Monday to hear the inaugural concert for its expanded sanctuary organ, here's a suggestion: Be ready for anything.

Someone may come up to greet you beforehand and turn out to be the evening's performer. His clothes certainly won't be a tuxedo or dark suit, but they're likely to sport Swarovski crystal accents. The music he plays could range from Bach to "Billie Jean" - that's right, the Michael Jackson hit.

"The organ is musical dynamite," organist Cameron Carpenter says. "But the fuse must be lit."

Carpenter, who declares that in the news release for the tour that brings him to Charlotte, has the matches in his hands.

They're among the most agile hands playing keyboards today, shown off in an array of much-watched videos on YouTube. When the camera strays from them, it often turns to Carpenter's feet, which are busy setting off more pyrotechnics on the pedals.

Many of Carpenter's specialties are showpieces of his own devising - from Debussy's "Prelude to the Afternoon of Faun," originally for seductive orchestra, to elaborations on "Billie Jean" and "Strangers in the Night." By the time he adds the likes of that to the preconcert chatting and bedazzled clothes, the traditional aura of classical music - not to mention organ music - is long gone.

"For me to be able to express myself and do what I want to do with the instrument in a really satisfying way, and to be much more successful as a performer ... I need to expand things beyond where they sit," Carpenter says in a telephone interview.

Carpenter's YouTube videos have racked up not only hits but comments. The sentiments range from adulation to disgust. St. Gabriel's director of music, Steav Bates-Congdon, comes down on the pro side. He thinks Carpenter is supplying "fresh air."

"Organists are supposed to be like me - old, dowdy fuddy-duddies who don't think anything happened after 1850," Bates-Congdon says. "That shouldn't be so. It's the most exciting instrument in the world."

Carpenter, he says, "is so far outside the box that he's creating a new box."

Not a typical path

Carpenter was raised in rural Pennsylvania. As a youngster, he sang in the American Boychoir - one of the most prestigious such groups in the country. He came south in the 1990s for high school at UNC School of the Arts.

Carpenter was an organ major, but his musical appetites didn't stop there. On the side, he made an organ arrangement of a titanic orchestral work: Gustav Mahler's Symphony No. 5. Mahler's music had grabbed him with "this overwhelming, massive emotional input that it gives you." He found it "deeply obsessing."

Did his teachers at the School of the Arts know what he was up to?

"Heavens, no," he says. "They were only aware of it because I was skipping class."

Carpenter went on to earn a master's degree from the Juilliard School in New York. Since then, though, he hasn't followed the typical organist's career path.

For centuries, the overwhelming majority of organists have relied on church jobs for part of their livelihood. But Carpenter has gotten by without one, he says, ever since a stint at the First Baptist Church of Winston-Salem. He's proud that he has built a full-time concert career.

Even though church music isn't Carpenter's field, St. Gabriel's Bates-Congdon thinks church organists can take a cue from his theatrical musical style. Starting into an organ arrangement of "For the Beauty of the Earth," a hymn celebrating nature, in a recent service, Bates-Congdon added electronic sound effects: first thunder, then advancing rain.

"Everybody loved it," Bates-Congdon says. "They didn't want to hear it all the time that way, but it just gave them an insight" into the hymn's meaning. Besides, he adds, Charlotte at the time was short of moisture.

"It was my version," he says, "of a rain dance."

The star of the organ

The music world has singers and instrumentals who are stars, Carpenter says, but no organists. He wants to change that.

"I'm attracting the largest organ audiences in the world," he says. "I'm doing that because I'm trying to push through musical boundaries."

As he sees it, his attire - which often includes skinny jeans, tight T-shirts or glittery shoes - fit into that. When audiences see him walk out, he says, "they immediately recognize that there's something different going on here."

The big difference comes with the music, of course.

The night before the interview, he performed for the first time the finale of that long arrangement of Mahler's Fifth Symphony in Los Angeles. He paired it with another arrangement of his: J.S. Bach's beloved Chaconne for violin, which was expanded for piano a century ago by pianist Ferruccio Busoni - and expanded further by Carpenter.

"I'm sure there's somebody reading up on Busoni today because of what I did last night," Carpenter says. "Or Mahler. But I bet there are a lot of people who are not reading up on Busoni or Mahler (but) were moved by the music. And that's the point."