“How to get better religious art is very simple: just commission an artist. Then ask him to act as an artist, with imagination, with freedom, with vision, with daring.” So said the painter Adolph Gottlieb, one of three Modern artists who worked on an innovative Millburn, N.J., synagogue in the early 1950s. That Conservative synagogue — Congregation B’nai Israel — is now renovating and expanding, and has lent some of its art to the Jewish Museum for a small but transcendent exhibition. “Modern Art, Sacred Space: Motherwell, Ferber and Gottlieb” explores a postwar phenomenon, a meeting of secular and spiritual agendas that would be hard to convene today. Back then, artists, architects, dealers and rabbis shared progressive ideas about art’s place in the world. Today Abstract Expressionism is sacrosanct, and Modernist Reform and Conservative synagogues like Congregation B’nai Israel are the norm for suburban Jews. But at the time the Millburn synagogue was being constructed, both the building and the art in it were audacious. Congregation B’nai Israel, designed by the architect Percival Goodman and completed in 1951, marked a drastic change from the Old World architecture of earlier American synagogues. A set of low, sprawling boxes in glass, brick and light wood, it exemplified utopian Modernism and the aspirations of American Jewish communities after the war. Just as novel as the synagogue’s architecture was the fact that it incorporated cutting-edge art by abstract painters and sculptors. The art world at midcentury was full of Jewish artists and intellectuals: the painters Jack Tworkov, Ad Reinhardt and Barnett Newman, to name just a few. But it was more common to find Jewish theology in a museum or gallery than Abstract Expressionism in a place of worship. The synagogue’s three large artworks — Gottlieb’s Torah curtain, Herbert Ferber’s exterior sculpture and Robert Motherwell’s lobby mural — make up the bulk of “Modern Art, Sacred Space,” which was organized by Karen Levitov, associate curator at the museum. The Ferber and Motherwell are on loan from Millburn; the museum owns the Gottlieb, because its textiles are too fragile for ritual use. (The synagogue now uses a reproduction.) The artists were chosen by Goodman, who had the trust of the congregation and its rabbi, Max Grunewald. In his search, the architect consulted the dealer Samuel Kootz, whose gallery on Madison Avenue was at the vanguard of American Abstract Expressionism. (He showed Gottlieb and Motherwell; Ferber exhibited with Betty Parsons). All three artists already had a mystical/spiritual dimension to their work. Ephemera on view at the museum give you an idea of how important the B’nai Israel project was to the New York art world. René d’Harnoncourt, the director of the Museum of Modern Art, spoke at the dedication ceremony. Publications, including Time magazine and The New York Herald Tribune, weighed in on the building and its art. Gottlieb’s Torah curtain is the largest of the three works, and the most striking. Made with crimson and amber velvet and metallic thread, it’s a smooth adaptation of the artist’s Jung-inspired “pictograph” paintings. Symbols, including the Lion of Judah and the Tree of Life, occupy their own rectangular compartments. The curtain is recognizable as Gottlieb’s, but it’s also a collaboration. The artist worked closely with the rabbi on the choice of symbols, and the final piece was sewn by the women of the congregation under the direction of Gottlieb’s wife, Esther. Motherwell’s lobby mural, “The Wall of the Temple,” was also a team effort. Though he wasn’t Jewish, Motherwell had studied with one of the great rabbis of art history, the Columbia professor Meyer Schapiro. Schapiro encouraged Motherwell to switch his concentration from philosophy to painting, and continued to mentor him as he became a successful artist. When consulted on the Congregation B’nai Israel project, Schapiro gave Motherwell a long reading list and advised him to visit the Jewish Museum. He also encouraged him to use representational imagery (something Motherwell rarely did in his painting), despite the biblical prohibition of “graven” images. Motherwell also used Surrealist ideas about automatic drawing and the unconscious to facilitate his artistic “conversion.” He tried to surround himself with Jewish iconography, so that images that emerged during his drawing sessions, he told a reporter from The Herald Tribune, “had a tendency to be Jewish.” You can’t fault him for trying. He made more than 15 studies for the mural, moving abstracted versions of Jacob’s ladder, the tablets of Moses and other symbols into various positions. The finished project has some of the hallmarks of gestural abstraction — loose brushwork, rough outlines — but it looks far from spontaneous, and not all that much like a Motherwell. Ferber isn’t as well known today as Motherwell or Gottlieb, but he was successful enough to have been included in MoMA’s “Fifteen Americans” show of 1952. (The dedication of B’nai Israel was delayed by several months so that his sculpture for the synagogue could be seen at the museum.) He was also a multitasker, a working dentist who maintained a practice throughout his art career and published articles in scientific journals. In his 12-foot-high relief sculpture, “And the bush was not consumed ...,” spiky “flames” of lead-coated copper leap out from the wall. Unlike Gottlieb’s curtain or Motherwell’s mural, Ferber’s piece comes across as aggressive and even threatening. The rabbi, who had suggested the subject of the Burning Bush, was initially taken aback by the work’s appearance; drivers on Millburn Avenue, where the Ferber was installed on the synagogue’s facade, were reportedly distracted. Photographs by Hans Namuth, Ad Reinhardt and others of Ferber and his assistants making the sculpture reinforce the work’s Abstract Expressionist bravado. In one, Ferber leans over the piece, a cigarette dangling from his mouth, looking very much like Jackson Pollock in Namuth’s famous film. Congregation B’nai Israel isn’t the only example of a place of worship for which Modern art has been made. Matisse’s chapel in Vence, France, also from around 1950, comes to mind. So does the remarkable stained-glass window that Gerhard Richter created just a few years ago for the Cologne Cathedral. Neither artist could be called a practicing Roman Catholic. Their works, nevertheless, embrace and enhance spirituality. The same can be said of Motherwell, Ferber and Gottlieb, who had varied attitudes toward religion but an unshakable belief in the power of abstract art.