Oftentimes, it is the unlikely decisions that seem the most obvious in hindsight.

When someone suggested to Minnesota composer Carol Barnett that she combine the sacred choral tradition with sparkling bluegrass music, her immediate response was, “Why not?”

The result is “The World Beloved: A Bluegrass Mass.” The Choral Art Society’s 60-voice group the Choral Art Singers will present Barnett’s masterful work at 7:30 p.m. Saturday at Woodfords Congregational Church in Portland.

The program also includes music by Eric Whitacre based on a poem by e.e. cummings and William Billings, regarded as the father of American choral music; Morten Lauridsen’s “Sure on this Shining Night,” based on a poem by James Agee; and three African-American spirituals: “Set Down, Servant,” “There is a Balm in Gilead” and “Same Train.”

Barnett’s “Bluegrass Mass” feels like a romp, said Robert Russell, who directs the group and teaches at the University of Southern Maine.

“It feels like a grand good time. There’s a personal touch to it, in the choice of texts. There’s a bit of crashing about, but mostly it’s lovely singable melodies,” said Russell.

Marisha Chamberlain wrote the libretto for the piece.

A bluegrass band will accompany the Choral Art Singers, along with soprano Kelly Caufield. The band includes Erica Brown on fiddle, Steve Roy on mandolin, Read McNamara on banjo, Matt Shipman on guitar and Amanda Kowalski on bass.

The piece, which Barnett wrote in 2009, brings the solemnity of the classical choir-based Mass together with the down-home snap of bluegrass.

“My highest hope is that listeners coming from one tradition — classical or bluegrass — and perhaps dubious about the other might discover something new and wonderful in the combination, as I have,” Barnett writes in her statement about the piece.

“Composing the music for ‘The World Beloved’ has given me the chance to write cheery sacred music — all too rare in a medium rife with staid and even lugubrious settings. And it’s brought me back to memories of music heard while visiting my grandparents, country music with a church flavor that told stories and came out of a scratchy old record player. Grandma would not have allowed dancing, but under the table I tapped my toes.”

Russell has long admired Barnett’s writing. She has written more than 100 choral compositions, an opera, more than a dozen orchestra and band compositions, and many pieces of chamber music.

“She is a woman of established reputation in Minnesota music circles,” said Russell. “Her choral writing is first-rate. So singable, so vocal, so wonderful. It is packed with beautiful melodies to sing, stem to stern.”

Russell is excited about working with the bluegrass band and with Caufield. The band includes many of Portland’s best-known acoustic musicians, and Caufield has a powerful voice. She was a student of Russell’s at USM.

“I loved her voice back then, and I love it today,” he said. “She has made a name for herself in the Broadway and popular music scene in Portland, and these songs fit her voice to a T.”

Russell is also excited about the prospects of returning to Woodfords. It’s been a long time since a Choral Art Society group has used the church as a performance venue.

“The sound is terrific,” he said. “In the chancel, our sound has the opportunity to mix and project on out, and the chancel is spacious enough that we do not feel cramped.” 

Staff Writer Bob Keyes can be contacted at 791-6457 or at [email protected]

Follow him on Twitter at twitter.com/pphbkeyes