In the Morningside Heights section of Manhattan, near Columbia University, stands a blocky 19-story limestone tower known to some as the “God box.”

Opened in 1960, the Interchurch Center (as it’s really called) stands today as a monument to the now-faded swagger of midcentury American liberal Christianity. These days, it houses a mixture of religious and secular offices, including one where people were gathered around a table on a recent afternoon debating the nature and fate of another midcentury phenomenon: the Commonweal Catholic.

Commonweal Catholics were educated, liberal-minded and middle-class, and aspired to assimilate into elite culture while bringing their Roman Catholic faith, education and sensibility with them. And today?

“The term isn’t as definite as it used to be,” said Matthew Boudway, senior editor of Commonweal magazine, which gave the type its name. But to him, it means being liberal in politics and theology, while also “thinking too hard” about how faith and the rest of your intellectual life mix.

Dominic Preziosi, the magazine’s editor, also at the table, laughed. “Sometimes way too hard,” he said.

The old-style Commonweal Catholic may no longer quite exist. But Commonweal magazine, which describes itself as the nation’s oldest independent lay-edited Catholic journal of opinion, is still very much here. And this fall, it is celebrating its 100th birthday with a gala, an anthology of its interviews over the years with prominent figures (Jorge Luis Borges, Reinhold Niebuhr, Martin Scorsese) and a 100-page centennial issue.