A room at New Life Christian Church in Polson fills with voices, flitting up and down the scales, as music director Christian Bumgarner prepares members of the Mission Valley Choral Society for their annual holiday performances.

This year’s “We Wish You a Merry Christmas” concerts begin at 1 p.m. Saturday, Dec. 17, at the St. Ignatius Mission and 2 p.m. Sunday, Dec. 18, at the Ronan Performing Arts Center. The selection includes all 12 movements of Vivaldi’s “Gloria” – described as “a joyful hymn of praise and worship” – along with a selection of sacred and traditional Christmas songs. A string quartet will accompany both performances.

Bumgarner, who was choir director at Polson High School until 2012, followed by a stint as headmaster at Mission Valley Christian Academy, has been a member of the group since 1989.

When he first started, “I just enjoyed singing.” But when members realized he was the high school choral director “they roped me in” to directing the choir, which has been in existence since the mid 1960s.

He’s held that role off and on since the 1990s, most recently taking the helm after former director Mason Niblack stepped down.

The choir currently has around 35 members, ranging from their early 20s to 80s. Bumgarner says some are former high school students.

They practice for the annual Christmas concerts for two hours every Tuesday, beginning in late September.

Bumgarner credits his “fabulous” accompanist Karla Gallatin for the choir’s continuity. “She makes it happen.”

“I don’t know why they put up with me,” he adds. “I razz them a lot, but they keep coming back for more.”

He suspects their commitment is fueled by “camaraderie – the joy of creating music together.”

That’s apparent at a recent practice, as choir members worked on “The Virgin Mary Had a Baby Boy,” a spirited West Indian carol. Bumgarner chides them for “not chewing that diphthong” on the word boy, and wonders if members have grammatical issues with “a-when the baby was born.”

“I know it’s not good English,” he tells them. “You don’t have to agree with it – just do it.”

“I try to make it as fun as possible,” he says, while realizing that many members have never sung publicly or haven’t since high school. Adult singers are different than the kids he spent so many years teaching.

“You’d think it’s the maturity, but it’s not always that. They’re just completely different animals,” he says. “I’m able to do more complex stuff with adults, which I just really enjoy.”

“I talk about tone quality, I talk about natural, free and vibrant – we’ve been hashing that over for the last three or four weeks … It’s very intense but they just seem to enjoy one another,” he says. “They’re very motivated.”

Some came back this year “because they know this is my last Christmas concert,” he says.

Bumgarner and his wife are moving to North Idaho next year to be closer to their 14 grandchildren, making preparations for the Christmas concert “kind of bittersweet.”

He’ll also be at the helm for the spring concert, typically held on Palm Sunday, which gives the choir a few months off before reconvening in February.

This weekend’s two 90-minute concerts are free; a free-will offering will be taken to benefit the choir. For more information, call 406-261-3304 or 406- 370-2076, or visit missionvalleychoralsociety.org.