Now, after 11 years, Aaronson is trading the Utah mountains for the lively, bustling Jewish community of suburban Los Angeles, home to the largest Jewish population outside of New York City.
On July 1, he will become senior rabbi at Temple Judea in Tarzana, Calif., one the nation's most prestigious synagogues. He will have a bigger staff, including several other rabbis, cantors, choir, musicians, religious schools, youth programs and endless committees. An interim rabbi, Jim Simon, will lead Har Shalom, while the congregation spends a year looking for a permanent replacement.
By all accounts, Aaronson leaves behind the kind of cohesive, accepting Jewish community he envisioned from the start.
How did he do it?
With music, skiing, wide-ranging, literate sermons, an informal style, energetic outreach, passionate commitment to social justice and a dollop of humor.
"You can't be Jewish on a desert island," he is fond of saying. "To enact Judaism properly, to truly live Judaism, you must attach yourself to a community."
Small beginnings • In the fall of 2002 months after the world turned its attention away from Utah's 2002 Winter Olympics Temple Har Shalom's new rabbi presumed he was now stationed in the country's backwater, home mostly to Mormons and conservatives. After all, he had never been to Utah.
Aaronson was reared in Philadelphia, went to college in Michigan, studied at a rabbinical school in New York City, filled an internship in New Jersey, lived for a year in Israel, served as assistant rabbi in Buffalo, N.Y., and Cleveland, and then spent four years in Perth as the only Reform rabbi in all of western Australia.
What he didn't expect, he now says, was what a "forward-thinking, vibrant place" Utah is.
"It is so much more than hiking, biking and trails," Aaronson says. "In the post-Olympic boom, development in Park City has been immense. It has become a cultural hub."
When Aaronson arrived, Har Shalom's tiny congregation of fewer than 100 families met in 1,200 square feet of rented space in Park City's Sage Building in the Prospector Square neighborhood.
The new rabbi's friendliness and approachability proved an instant hit.
"He seemed accessible," recalls Jonathan Klein, who has served on the synagogue's board. "He didn't take himself too seriously, but he also has a lot of depth that you don't realize right away."
Doug Goldsmith, another board members, adds, "He greets everyone with a huge smile and belts out, 'How's your family?' His presence filled the room and made everyone feel incredibly welcome."
At the first staff meeting, Aaronson was "saying things that I thought were a little off the wall," recalls Joy Erickson, Har Shalom's membership director. "Turns out he was joking and I could not tell. To this day I'm not always certain when he is serious and when he is teasing."
But there was no mistaking one of his signature skills: music.
As an avid guitarist with eclectic tastes from classic rock to jazz and Frank Sinatra, Aaronson also composes liturgical music for Shabbat worship services.
Congregants credit his music for setting a celebratory yet peaceful tone.
During one of his first services with young children, the rabbi was playing his guitar and leading the little ones in song.
"He began walking back and forth across the bima [platform] and the children lined up behind him, following him wherever he went, singing with big smiles on their faces," Erickson says. "I remember thinking he was like the Pied Piper … people would follow him anywhere."
And so they did.
Har Shalom's membership tripled as Aaronson's style and energy attracted newcomers.
His sermons were sometimes light, but always potent. The rabbi drew his topics and opinions from a diverse reading menu, including sayings of the 12th-century Jewish sage Maimonides to books about the Middle East, American politics, history, even contemporary thrillers. He also tied in references to his favorite football team: the Philadelphia Eagles.
"Sometimes he talked about current events, theological matters, Israel or morality," Klein says. "You weren't sure what you were going to get, but it was never boring."
Aaronson's approach was "thoughtful and often challenged our thinking," Goldsmith says. "He usually had a [question-and-answer session] at the end. Josh always encouraged us to express our opinions about what he was teaching and was very accepting of all opinions."
The ultimate goal, of course, was community building and not just among Jews.
An expanding circle • True to his original vision for Har Shalom, Aaronson began immediately cementing relationships with like-minded friends religious or otherwise in Park City.
While Aaronson's good friend, the Rev. Bob "Father Bob" Bussen, then the priest at St. Mary of the Assumption Catholic Parish, created a way to worship on Utah's slopes, the rabbi introduced "Ski Shul," a shortened Shabbat service at the Sunset Cabin at Deer Valley every Friday at 3 p.m., which drew worshippers from around the world.
He formed interfaith relationships with neighbors, including the Rev. Charles Robinson, pastor at St. Luke's Episcopal Church, and Dana Williams, mayor of Park City. He worked with Mormons on service projects and visited the LDS Oquirrh Mountain Temple during its public open house.
Within the faith, he launched standing-room only adult-education courses, drummed up support for the United Jewish Federation, and took some congregants to Israel.
Goldsmith says he always felt he had missed out by not having a bar mitzvah, so when Aaronson begin offering a class in Jewish history and scripture, he signed up. Then, together on a trip to Israel, student and rabbi hiked to the top of Masada, Goldsmith says, "where I was able to read from the Torah and celebrate my bar mitzvah."
The next week, Goldsmith's son celebrated his bar mitzvah with Aaronson while overlooking the old city of Jerusalem.
"Rabbi Aaronson," he says, "was by our side at so many milestones."
That's what most Har Shalom worshippers, including the rabbi, will remember: the relationships built around births, deaths, weddings, bar and bat mitzvahs all those moments that make up the collective Jewish life.
The rabbi "guided us from being a small, close-knit group to becoming a congregation of 300 families housed in a beautiful temple," Goldsmith says. "He gave us the confidence to do what we never thought was possible."
Aaronson leaves his Utah fold, says Goldsmith, "a much wiser, more religious, and well-educated group."
Now he's off to a very different kind of religious terrain.
About Joshua Aaronson
Family • wife, Debora Aaronson; children, Hanna, 18, Harry, 15, Emma, 13
Education • Bachelor's, University of Michigan; master's, Hebrew Union College-Jewish Institute of Religion in New York, where he had his rabbinic ordination; senior rabbinic fellow at the Shalom Hartman Institute in Israel