JERUSALEM — THERE was a time not so long ago when Avraham Burg was viewed by many Israelis as proof that the inherent tensions of Zionism — religious versus secular, insular versus worldly, Jewish state versus state of all its citizens — could be reconciled with grace. Here was a religiously observant Jew with a cosmopolitan outlook, a decorated paratrooper who believed deeply in peace with the Arabs, an eloquent, fast-rising public figure accessible to a broad range of citizens.

Widely known by his nickname, Avrum, Mr. Burg, a happily married father of six and the son of one of Israel’s most admired and longest-serving government ministers, was talked about as a candidate for prime minister. Long before his 50th birthday, he led the World Zionist Organization and served as speaker in Parliament.

But four years ago Mr. Burg not only walked away from politics, but also basically walked away from Zionism. In a book that came out last year and has just been translated and released in the United States, he said that Israel should not be a Jewish state, that its law of return granting citizenship to any Jew should be radically altered, that Israeli Arabs were like German Jews during the Second Reich and that the entire society felt eerily like Germany just before the rise of Hitler.

In other words, rather than reconciling the country’s complex tensions, Mr. Burg ended up imploding from them.

“I realized something about myself and Israel that frightened me,” he said recently, looking back over the past few years. “I realized that Israel had become an efficient kingdom with no prophecy. Where was it going? What is a Jewish democratic state? What does it mean that Jews define themselves by genetics 60 years after genetics were used against them?”

Israel is no stranger to self-examination. Its leaders and thinkers, indeed many of its average citizens, are aware that nearly everything about the place defies normal categorization and is subject to debate. This is a source of both pride and irritation. But many said Mr. Burg, 53, was not just asking delicate questions. He was poisoning the well from which the nation — and he — had long drawn their water.

As Ari Shavit, a writer for the newspaper Haaretz, said to him in an interview when the book was published here: “Your book is anti-Israel in the deepest sense. It is a book from which loathing of Israeliness emanates.”

Mr. Burg rejected that accusation and still does. He wrote from love, he said, and if the issues he raised were troubling, if they caused a stir, that was very much his aim.

There is no doubt that he raises some serious questions: Is Israel too focused on the Holocaust as a touchstone of history? Can it stay both Jewish and democratic over the long term, or is it time to look for another model? What kind of future is there for Israeli Arabs?

Less clear, however, is whether Mr. Burg has provided any serious answers. This is partly because his book and discourse vacillate between two poles: congratulating Jews and the Zionist movement for their success so far, but warning them that they are turning into a kind of self-justifying Sparta, a warlike state on the verge of tragedy.

His central point is summed up in the English title of his book: “The Holocaust Is Over; We Must Rise From Its Ashes” (Palgrave Macmillan). The Nazi slaughter of six million Jews, he says, has become the central theme of Israeli life, dominating it in a way that distorts the country’s outlook. Teenagers are sent on trips to Auschwitz; every enemy of Israel (Yasir Arafat, the Palestinian leader; Mahmoud Ahmadinejad, the president of Iran) is viewed as the reincarnation of Hitler.

MR. BURG has shifted the title of his book over the years. When he was writing it, he called it “Hitler Won.” When he published it in Hebrew he called it “Defeating Hitler.”

Partly, he said in the interview, his thinking is evolving, and partly his American editors made some smart cuts and suggestions. But it also seems clear that he has modified and adjusted his arguments, especially for a foreign audience. The English version does not have some of his more alarming assertions in the Hebrew one — for example, that the Israeli government would probably soon pass the equivalent of the Nuremberg laws, with provisions like a prohibition on marriage between Jews and Arabs.

Asked what precipitated his initial shift from mainstream public figure to more marginal public scourge, Mr. Burg pointed to a process that began in 2001 when he ran for leadership of the Labor Party and lost in a tight race that he says was stolen from him through back-room deals.

It was not so much the loss, he asserted, as the realization that he had poured his heart and soul into trying to win something that he had thought so little about.

“I knew how to get elected, but what was I going to do once I got there?” he recalled thinking. Maybe, he felt, it was lucky that he lost.

He took five weeks off and walked part of the Appalachian Trail in Connecticut, New York and New Jersey by himself. “In five weeks I met 11 people, none of them Jewish,” he said. He realized that life here was too insular for him, that it was time to step outside the provincial concerns of the extended Jewish family.

Mr. Burg, born and raised in one of West Jerusalem’s most admired neighborhoods and a graduate of the Hebrew University, comes from one of the country’s iconic families. His father, Yosef Burg, barely escaped the Nazis when he left Germany in September 1939 and was a government minister for nearly four decades. His mother was a survivor of the Arab massacre of Jews in Hebron in 1929.

But Mr. Burg wanted a clean slate. He decided to leave politics and build an international business, stop writing bills and news releases and write books, stop taking short runs and train for marathons. And so he has. He is co-owner of a company that takes over failing businesses and rebuilds them for sale, has published two best-selling books and is a long-distance runner. He travels frequently and added a French passport to his Israeli one, a benefit of his wife’s origin.

The many friends and acquaintances of Mr. Burg — a man of great charm and wit, with a large social appetite — have been left bewildered by it all, saying the soft, flowery answers he has offered to his big, tough questions have left them cold.

Tom Segev, for example, a left-wing historian and Haaretz columnist, said in a review that the book was “one of the most spaced-out and in-your-face books this country has seen in many years.”

WHAT are Mr. Burg’s prescriptions? He wants a new Jewish identity focused not on the particular but on the universal, asserting that “if we do not establish modern Israeli identity on foundations of optimism, faith in humans and full trust in the family of nations, we have no chance of existing.” He wants Israel to dismantle the Yad Vashem Holocaust memorial in Jerusalem and replace it with the headquarters for the International Criminal Court, making it the epicenter of international prevention of genocide.

In truth, he has gained almost no traction here with such recommendations. Yet what is perhaps most interesting of all is that Mr. Burg continues to play a public role in Israel. He is invited to speak to young people, he writes occasional opinion columns, and he is greeted warmly, even embraced, in this city’s cafes. This may be because, despite it all, Avrum Burg is family. And whether he likes it or not, Israelis look out for family.