As I write these words (on May Bank Holiday, Erev Lag ba-Omer) I'm just getting ready to spend a week in Israel where, as Visiting Professor at the Hebrew University, I'll be meeting and teaching not only Israeli academics, but also the future rabbis and educators of British and American Jewry.

My visit coincides with the last week of the Israeli election campaign. Thus far, not much in policy terms divides the leading candidates. But a great deal divides Israeli society. Religious and secular, Ashkenazi and Sefardi, sabras and new immigrants - the rifts run deep. Civility is at a minimum. Politics has become partisan rather than an exercise in pursuit of the common good. Groups demonize their opponents. One side describes the other as a threat to democracy. The other sees its counterparts as a threat to the Jewish character of the state and calls them "Hebrew-speaking gentiles". Doubtless Israel will survive. Yihyeh beseder, as we have learned to say. Israel is not the Balkans. Let's not over-react.

But the historical precedents are not good. Only twice before, in the days of the First and Second Temples, has the Jewish people known independence, sovereignty, statehood. On both occasions it failed to sustain them because of its inability to contain internal conflict. In the First Temple period, after a mere three generations of kingship, the kingdom split in two: Israel in the north, Judah in the south. Both were defeated, the north by the Assyrians, the south by the Babylonians. In the days of the Second Temple, not long after the stunning victory of the Maccabees, Jews were once again riven by dissension, religious and political. The two attempts to recover independence from the Romans - the Great Revolt in 66 C.E. and the Bar Kochba rebellion sixty-six years later - ended in disaster, not least because Jews (valiant fighters then as now) proved totally incapable of a unified force. Josephus, an eye-witness of the destruction of Jerusalem, paints a vivid picture of Jews within the beleaguered city more intent on fighting one another than on fighting the enemy outside. Plus ca change . . .

The questions raised by our past and present are profound. We coped with poverty. Can we cope with affluence? We endured slavery. Can we endure freedom? We knew what it was to sustain ourselves in exile. Can we do the same in our own land? Jews survived powerlessness. But can we handle power? Above all, can the Jewish people create a self-governing nation cohesive enough to transcend the conflicts of class, culture and creed that destroyed national unity in the past? This is the question that haunts the pages of Jewish history.

It would be wrong to over-dramatise. Wrong too, to forget the monumental achievements of Israel thus far. In a mere fifty years it has fought and won wars in which its very survival was at stake. It has rescued, housed and integrated Jews from more than a hundred countries. Its population has grown almost a thousand per cent. It has developed one of the great economies of the modern world. (Shimon Peres used to dream that Israel would one day become the Hong Kong of the Middle East. Earlier this year, visiting Mr Tung Chee-Wha, the new Chinese governor of Hong Kong, I heard him express his admiration of Israel's hi-tech economy. His dream? That Hong Kong should become the Israel of the Far East!) And of all the new nation-states created since the Second World War it has sustained the most open and lively democracy. This is an astonishing record. Even Herzl, who used to say, "If you will it, it is no dream", never dreamed of such things. The Israeli novelist David Grossman began a speech on Israel's fiftieth anniversary with the words, "Israel is the only utopia which has actually happened." All this is wondrous in our eyes.

But there is an ancient tradition in Judaism -one of the greatest of our contributions to the civilization of the West - called prophecy. The prophets were not magi, seers, oracles, mystics. They were political realists as well as visionaries. They were far and away the most acute observers of their age. They foresaw the future because they were rooted in the past and thus protected against the myopia of the present. Their intense religiosity - their sense of the presence of God in history - made them immune to short-termism, the occupational disease of politicians, past and present. They had a foothold outside of time, so they could understand their times - almost as an air traveler today can see geography in a way unimaginable to those who have never flown.

A politician asks, What shall we do tomorrow? A prophet asks, Where will it end? In the midst of affluence he sees decay. In the midst of catastrophe he sees consolation. While others see a solid building, he sees the eventual ruin. While others weep over the ruins, he sees the rebuilding. Like an engineer he detects the hairline fault that will one day become a fracture. Like a botanist he identifies the seed that will one day be a tree. Today, Israel needs its prophets, and they are nowhere to be heard.

The prophets understood one thing about a Jewish state, obvious at a distance but barely visible close to hand. From the dawn of history, Jewish existence has never been quite like that of other nations. We were a small people at the crossroads of empires - strategically situated between Europe, Asia and Africa, occupying tenuous space, always liable to attack, never able to rival the surrounding powers in numbers or military might. Israel has always survived against the odds. It has had to call on supreme resources of energy, morale and dedication. If an artist were to paint a picture epitomizing Jewish destiny, it would surely carry Zechariah's superscription: "Not by might nor by power but by My spirit."

Jews cannot survive for long without a double measure of that spirit. The idea put forward by "post-Zionists" today, that Israel can become a secular liberal democracy without any specifically Jewish character is a farce destined to end in tragedy. Israel is not Switzerland - and even Switzerland owes much of its character to its strong Calvinist traditions. Equally mistaken is the view taken by many religious Israelis, that Judaism can survive in a Jewish state behind ghetto walls, in essentially sectarian forms. It may be able to do so in the Diaspora, where questions about the Jewish character of the public domain simply do not arise. It cannot do so in Israel, where religious issues are part of the very texture of national culture and debate.

And so, on Shavuot 5759, we find ourselves retracing our steps back to the very first Shavuot and to our birth as a nation under the sovereignty of God, with the Torah as the first ever written constitution assented to by an entire people, in the great, eternal covenant whose words have echoed through our history ever since. No other nation ever became a nation prior to possessing a land and a state. And to this day Israel is the supreme example of a people whose very existence as a state depends on its integrity as a nation with a collective vision, a shared faith.

This is Israel's next great challenge, and it is ultimately a spiritual one - not in a narrow sense but in the full majesty set out once and for all time by Israel's prophets. They foresaw a society of justice to the weak and compassion to the poor, of ethical beauty and spiritual grandeur, in which "each of you will invite his neighbor to sit under his vine and fig-tree", a society to inspire its citizens and compel the admiration of a sometimes hostile world.

It can be done. No one who knows the achievements of Israel thus far can doubt that it can be done. And no one who knows the history of Israel can doubt that this is the challenge for which we have waited for two, three, four thousand years. Is it on the current agenda of any of the political parties? Perhaps not. That is why at least some religious voices in Israel must make the move from politics to prophecy. For if not now, when?