Larry Lowenthal is executive director of the Boston branch of the American Jewish Committee. To judge by his public statements and writings, Mr. Lowenthal's idea of a faithful Jew is someone who opposes the nomination of Judge John Roberts to the U.S. Supreme Court, supports gay rights, abortion and euthanasia, and demands a strong separation of church and state. After all, as Mr. Lowenthal concluded approvingly in a July op-ed for the Jewish Advocate, Jews are "the most liberal" and "the least religious people in America."

Imagine his consternation when an avalanche of emails from Russian Jews began to pour in to the Web site of the Jewish Russian Telegraph, a daily blog, in response to his article. About 100 people wrote to say that Mr. Lowenthal needed to stop making "outrageous statements" on behalf of people whom he doesn't represent.

Alex Koifman, who arrived in the U.S. from Belarus in 1978, and whom Mr. Lowenthal trained for his position as a board member at the Boston AJC, criticized his old teacher for overstepping his bounds, saying: "Since when are these concerns [abortion, gay rights, and church-state separation] concerns that are specific to the Jewish community? These are the Left's concerns."