Traditionalists frowned when St. Columba opened in St. Paul's Midway area in 1950. Flat-roofed, with slab limestone walls, slit windows and a floor plan shaped like a fish — an early Christian symbol — the building resembled no other Catholic church in the Twin Cities.

Sure, the design by Barry Byrne, a former pupil of Frank Lloyd Wright, had some inspiring details, including an enormous coved ceiling painted in periwinkle that hovered above the sanctuary like an angel's halo. But where were the spires and arches? What about the stained glass? It verged on heresy.

Even today, St. Columba's character seems a little kooky. Yet it was neither the first nor last sacred structure to raise eyebrows in Minnesota in the postwar era. As congregations and architects began to experiment with new forms of worship, construction materials and ecclesiastical building styles, hundreds of churches and synagogues sprang up. The result is a local landscape dotted with midcentury modern houses of worship — some still breathtaking, others so plain we barely notice them anymore.

Religious revival swept the United States like a Pentecostal wildfire after World War II. The proportion of Americans claiming religious affiliation jumped from less than half to nearly two-thirds between 1946 and 1955.

As congregations grew, church-building boomed: Mount Olivet, a prosperous flock in south Minneapolis, erected a giant building with all the Gothic trimmings — a bell tower, tracery windows, stone buttresses — and pews enough for more than 1,000. But many churches — particularly new ones established in the proliferating suburbs — couldn't afford stone sculptures and golden orbs. To meet their needs and budgets, architects evolved new forms and experimented with less expensive materials.

The most influential church design to emerge from this era was Christ Church Lutheran in south Minneapolis, says Larry Millett, author of the recently published "Minnesota Modern: Architecture and Life at Midcentury." When Pastor William Buege realized that nothing short of a miracle would provide the dollars necessary to afford a traditional church design, he took the advice of a friend and sought out Eliel Saarinen, the Finnish architect of international renown who had designed a simple brick church free of historical references for a congregation in Indiana.

The boxy brick-and-Mankato-stone church that Saarinen produced for Buege's congregation had top-notch acoustics and an austere aesthetic that seemed to invite meditation and self-reflection. Today, Millett writes, Christ Church "looks very familiar because it has so many imitators."

Equally popular, however, was the A-frame church. Modeled on old churches of northern Europe, the ribs of these soaring structures (sometimes fashioned into a high arc) often were made of wood laminate — a newly developed and cheap material. Wide expanses of clear or single-colored glass filled the gables, and the skyward-straining silhouettes seemed to mollify congregants who believed even modern churches should pay homage to the medieval.

Not all A-frame churches looked like Swiss ski lodges. In the hands of a talented architect like Minnesota's most famous modernist, Ralph Rapson, the form became origami. Rapson's design for St. Peter's Lutheran in Edina uses eight peaks to form a vault over an octagonal sanctuary. Capped with a cross, the building resembles nothing so much as a crenelated Christmas ornament. Inside, worshipers surround the altar — creating a theater-in-the-round experience that also grew popular in midcentury ministry.

Rapson wasn't the only architect in favor of tweaking traditional liturgical design, where the celebrant stood like a gatekeeper between worshipers in the nave and the holy altar in the chancel. Minnesota architect Edward Sovik, who designed Westwood Lutheran in St. Louis Park, advocated vigorously for spaces with flexible designs, or "non-churches" as he called them. A prolific writer as well as designer, Sovik often substituted chairs for pews and wooden tables for marble altars — both of which could be reconfigured as a congregation's needs changed. His beliefs in ecumenicalism also led Sovik to strip many of his designs of anything that would have suggested they were Protestant, Catholic or creed-aligned at all. Shorn of such symbols, however, modern churches often became nondescript — the kind of structures that caused architecture critic Frederick Webber to rant: "Modern is a craze just now, yet its very ugliness will prove its own destruction, for people will tire of it."

People did eventually tire of Modernism, of course. But the style flamed out in spectacular fashion only as the 1960s drew to a close, merging with the fantastic dreams of the Space Age. Minnesota has only a few examples of late Modern architecture (hippy-dippy California was the epicenter), but among them is Beth El Synagogue in St. Louis Park, dedicated in 1970. Designed by Bertram Bassuk, its dramatic sloped roof could easily be mistaken for a ski jump. Its upward thrust reminds some of the U.S. Air Force Academy Cadet Chapel in Colorado Springs, but, in fact, the design was modeled on the Tent of Meeting, a portable shrine for the Ark of the Covenant.

Churchgoing began to decline as America entered the 1970s, and, with it, the ecclesiastical building boom stopped. But Modern churches remain part of our contemporary streetscape. "We don't think of the midcentury period as being religious," Millett says. "Yet it was a really great age for building churches.

"I don't think we've done anything better."

Joel Hoekstra writes about architecture.