For every great theatrical idea, there’s a story — a tale of an “aha” moment when the stars align, the planet shifts and something wonderful suddenly springs to mind.

The Church of Great Rain — a new live radio show that has become a once-a-month Sunday night sensation at Red Bicycle Bistro & Sushi — had such a moment.

It came last September, when Island music impresario Pete Welch e-mailed Greg Parrott, asking if he’d like to play a Sunday night gig at the Bike.

Parrott, who along with fellow musician Frank Hein makes up the folk rock duo Great Rain, thought that sounded like fun — and then he had an even better idea.

Sensing what he called a “divine opportunity,” Parrott replied to the e-mail, asking Welch if he could bring along a few extra musicians.

It seems Parrott and Hein had been getting together to jam with a group of Island musicians every Sunday morning at 11 a.m. and, in tribute to the day and time, had begun to refer to the sessions as “The Church of Great Rain.”

“The jokes started right away,” Parrott explained. “We said, ‘Honey, I’m going to church.’ It sounded better than ‘Honey, I’m going to someone’s studio to play guitar and drink beer.’”

Parrott said he went back to Hein and the rest of his “church brothers,” after receiving Welch’s e-mail, and asked, “What do you think of evening services at the Red Bicycle?”

“It’s unbelievable what happened since then,” Welch said. “It just gets better and better.”

The Church of Great Rain — now in its eighth month at the Bike — has evolved into Vashon’s own version of “Prairie Home Companion” and found an enthusiastic audience drawn to its high-spirited blend of local music, comedy, invited guests and tales of Island life.

The cast has also grown to include an ensemble called The Holy Roller Radio Players, who serve up comedy sketches between the show’s musical interludes.

Led by “O” founder David Godsey, who plays the part of the Right Reverend Hunter Davis in the show, the players include VoV stalwarts Jeff Hoyt, Susan McCabe, Jeanne Dougherty, Karen du Four des Champs and Karen Biondo.

Other cast members include Mik Kuhlman, Janet McAlpin, Jim Farrell, Cindy Hoyt, Steffon Moody and Justine Freese.

“The whole point of the show is to celebrate Vashon,” said Godsey. “It’s a place we love, with its own peculiarities and also things that are universal.”

Godsey’s involvement in the show has expanded in recent months.

“David has reached out to the community of writers and performers,” Parrott said. “We’ve been getting more and more talent, and more and more content to work with. Jeff Hoyt could be a Garrison Keillor on his own.”

Godsey’s involvement has also allowed Parrott and Hein to focus more on the musical aspects of the show, as well as time to dream about how the show might expand its reach beyond the shores of Vashon.

“We’re building something special,” Parrott said, while describing how he and Hein would like to podcast the show and find other ways to make it available for wider audiences.

“Our ambition is to do all this while not coming across as ambitious, otherwise it wouldn’t be Vashon,” he joked. “But we want to see how much merit the concept has. We think we have the talent, if it is presented in the right way, to have some national appeal.”

Parrott said that in order to keep growing, the show needs more volunteers, including video and sound editors and stage managers. He also hopes Islanders will contribute ideas at the show’s blog site at www.churchofgreatrain.spaces.live.com.

For now, he and Godsey are both excited about the church’s growing Island congregation.

“It has picked up a lot,” Godsey said. “I hope people will discover this little gem that takes place once a month, and come out and see it.”

Church of Great Rain

The Church of Great Rain happens on the last Sunday evening of each month at Red Bicycle Bistro & Sushi. This month’s show starts at 7 p.m. Sunday, May 31, with special guest singers Angela Reed and Vashon Opera Company’s Jennifer Krikawa.

The show will also feature the Holy Roller Radio Players and the Church House Band.

‘Church’ is broadcast on VoV-TV, Comcast Channel 21. For show times, visit www.voiceofvashon.org.