When is a rabbi not a rabbi?

When it's Jacob Voorsanger, a Congregation Emanu-El "rabbi" from 100 years ago.

Long considered one of the most famous rabbis in San Francisco history, Voorsanger was, in fact, never ordained.

That surprising piece of new information turns up in historian Fred Rosenbaum's new book, "Visions of Reform: Congregation Emanu-El and the Jews of San Francisco 1849-1999."

In his previous book on the history of Emanu-El, "Architects of Reform," Rosenbaum went along with the crowd and called Voorsanger a rabbi.

But that was published 20 years ago. Rosenbaum has since done more research into that subject, and many others.

The result is a 534-page tome that paints a much richer portrait of Emanu-El. Rosenbaum adds new chapters and inserts facts into the new book that were unknown to him when the 1980 version came out.

For example, in the first chapter, he incorporates excerpts from some letters written by Rabbi Julius Eckman — the synagogue's first rabbi — that he didn't have access to previously.

Eckman was old school, resisting reforms typical of West Coast Judaism in the 1850s. His letters blasted the inclusion of women as synagogue board members, referring to their "so-called emancipation" as "ridiculous foolery."

He was appalled that his congregants "would leave synagogue upon hearing that a steamer had arrived with mail and newspapers," and that they "would throw wedding receptions in downtown taverns."

The letters further revealed Eckman's distress over the "madness in raving after riches" he found in San Francisco. Flash ahead to the dot-com Bay Area of 2000, and Eckman would no doubt be writing the same letter if he were alive today.

As for Voorsanger, Rosenbaum, who is 52, simply uncovered new research on him "that was done after my book came out in 1980."

The undeniable conclusion: Although he has always been listed as Emanu-El's senior rabbi from 1886 through 1913, the man whom Rosenbaum describes as "one of the luminaries of the Reform movement's second generation" was never ordained.

"Everyone assumed that he had been, and everyone referred to him as a rabbi," Rosenbaum said in a recent interview. "[However he] never claimed rabbinical ordination, only that he had been 'educated' at the seminary in Amsterdam."

Rosenbaum said the Voorsanger revelation is emblematic of a larger story.

"In the West in those days, people came here without all of the proper credentials but were judged by what they were able to do. He was a great spiritual leader nonetheless, and a great scholar, too."

The new book was commissioned by Emanu-El — the largest congregation in Northern California, with a current membership of more than 1,700 households — in conjunction with its 150th anniversary.

It was a dream-come-true project for Rosenbaum, who has written several books and articles on Bay Area Jewish history. He is also the founder of the Berkeley-based Lehrhaus Judaica, the largest school for adult Jewish education in Northern California.

"It's a rare opportunity," Rosenbaum said, "for a historian to go back to a book he or she has already written and to make it more relevant."

As an overall theme, Rosenbaum said many of his additions in "Visions of Reform" are women's contributions not only to Emanu-El but to San Francisco's Jewish community at large.

Jewish women were "at the forefront of San Francisco society in the 1890s, in terms of movements like temperance and suffrage," he said. "Six Jewish women were physicians in San Francisco, which was highly unusual at the time."

Rosenbaum said Jewish women were also writers and artists. "They were breaking the mold of the Victorian expectations for women," he said. "I think I dealt with that inadequately in the 1980s version."

In addition to including material that he didn't know about previously, Rosenbaum serves up all-new material in the last 2-1/2 chapters that many readers might not be aware of.

In the final chapter, for example, he writes that Rabbi Mark Schiftan was so mad after the sex scandal involving Rabbi Robert Kirschner that he "did not speak to Kirschner for the next six years."

Schiftan, who worked under Kirschner and took over as interim senior rabbi after Kirschner's resignation in 1992, was "absolutely appalled by his predecessor's behavior," Rosenbaum writes.

"He couldn't even bring himself to move upstairs to the senior rabbi's office, which in his mind had been 'tainted' by the immoral conduct that had taken place there."

"Visions of Reform" is more than twice the size of the 241-page original. Most of the new pages cover the period from 1980 through the end of the 20th century.

"The most important thing I was able to do in this book was convey the turn in the temple since 1985," Rosenbaum said, "and the response of this temple to the trends in larger society and in the Jewish community overall.

"That's what was so satisfying and rewarding about this project. The temple is such a different place today than it was when I wrote the first book in 1980."

The last chapter, "Temple of the Open Door," discusses how the synagogue has embraced innovations such as hiring a female cantor, Roslyn Barak, and a openly lesbian rabbi, Sydney Mintz.

It also discusses Emanu-El's controversial decision in 1996 to offer voluntary dues for the first year of membership.

Citing a study on that program, Rosenbaum quotes a woman in her 40s: "I always had a perception of…Emanu-El and I did not fit into that. I mean, it was always…the rich Jews of San Francisco. I felt like I'd have to go out and buy a whole new wardrobe to go to…Shabbat services. Of course, that's not true."

Then again, many of San Francisco's wealthiest Jews have been members at Emanu-El. Rosenbaum touches on many of them as he writes about the synagogue's history from the Gold Rush through the 1906 earthquake, the Depression, two world wars and the Holocaust.

"Today's Emanu-El may be placed on a continuum that goes back…to the founding of the congregation during the Gold Rush," Rosenbaum writes. "For while the visions of Reform have greatly differed during a period of seven generations and 11 senior rabbis, the overall aim has been the same: to adapt an ancient faith to contemporary reality, to modify Judaism in order to preserve it."