Sir Jonathan Sacks, Chief Rabbi of the United Hebrew Congregations of the Commonwealth, has just returned from delivering his Thought for the Day on Radio 4. "When in history did a rabbi have to deliver a message to an audience which was 99.9 per cent not Jewish?" he jokes. Preaching to people who are not fellow believers - indeed, not believers at all - is a challenge. It's about "empowering moderation", he says.
Dr Sacks, who describes himself as "an anti-establishment figure in an establishment position", knows all about moderation. He is not just a noted theologian but also a philosopher: he came to prominence with his 1990 Reith Lectures, a polished look at the persistence of faith. Since then, there has been a steady flow of philoso-phical works, from The Politics of Hope (1997) to the controversial The Dignity of Difference (2002). But surely theology and philosophy, like oil and water, do not mix. "Think of me as a lapsed heretic, if it helps," he says, chuckling. "Today you need voices within the great faiths that are both with-in and without"; without that, he says, "very bad things happen".
Yet why should anyone need faith in a secular age in the first place? Dr Sacks dismisses the idea that we are living in secular times. On the contrary, "we are undergoing the de-secularisation of the world". Secular nationalism died in Europe after the Second World War, and "it is dying throughout much of the Arab world at the moment". The power of "reason without presuppositions" has evaporated. Even our belief in science is in crisis. Far from curing all evils of the world, it has become "the source of a whole new load of evils". The notion of the greatest good for the greatest number has been reduced to a "personal-choice ethic which says, 'let everyone do what they like so long as they are willing to pay the price'". None of those systems actually delivers meaning. "They don't even deliver happiness or safety, for that matter." So religion is the only place you can find meaning.
But the perpetual search for meaning need not end with enlightened religion. "Religion does not do power very well," he says. "The Bible is terribly sceptical of political power." Hence there is always a danger of "politicised religion". Just look what happened in former Yugoslavia; look at what is happening in Iraq now.
Can religious authority ever be res- ponsible or accountable? "That's a tough one, whichever way you look it." There are two kinds of religious authority. There's the top-down ideology, as in the Catholic Church, and the bottom-up model that Judaism and Islam are a part of. Both have inherent dangers. "If it is a top-down system you worry about dictators and hate-mongers, and if it is bottom-up you worry about waves of mass emotion. The only safe path is to make religion in some sense accountable to reality."
Reality - or rather, the "reality principle" - figures large in Dr Sacks's thought. The religious personality, he suggests, has become rather schizophrenic. "There are more young Jews in religious seminaries today than at any other time in history. There are also more young Jews in university today than ever before in history. And the contact between them is less than ever before in history. I compare this to a cerebral lesion, a rare form of brain damage where the left and right spheres of the brain are intact but the connection between them is broken. Then you get a dysfunction in the personality."
It is the reality principle that connects the two sides. It stands outside faith and breaks through totalising systems and persecution complexes. Religion as a total system is invulnerable to the outside. "You can get a Jim Jones, or a David Kor-esh. Somehow you have to make religion accountable to democracy, to health, to education, and somehow you have to make it accountable to modernity."
It was exposure to the reality of modernity that changed Judaism. However, the process of exposure does not happen all at once. Muslims are latecomers to it, he suggests. "What Muslims are going through now, Jews went through in the first half of the 19th century. Judaism fractured into more pieces than at any time since the last days of the second temple. You had religious and secular. Within the religion itself, you had Orthodox and Reform and many shades in between." Islam is going through a similar process of fragmentation. "It is a very difficult time for Islam. I can identify with that."
So, does he see any common ground between Judaism, Christianity and Islam? "The assumption is that if we have a lot in common then we are inclined to agree." Yet the opposite is true. Even the agreement that the three monotheistic faiths are the true children of Abraham leads to disagreement. Dr Sacks argues that we need to focus on the humanitarian aspects of these faiths: "Like feeding the hungry and the sick - that is something that Jews, Christians and Muslims can buy into, because it's not based on theological belief." We are back to the reality principle.
The pace of change makes the religious life even more difficult. "We are going through major systemic change," Dr Sacks suggests. The driving force for this, now as before, is communications technology: he recalls that the Reformation was "a response to the birth of printing". We are experiencing a similar process through the globalisation of communication via satellite television and the internet. The turning points in history appear shortly after the invention of a new technology. "Judaism was born," he argues, "with the birth of the alphabet. Christianity was born with the birth of the codex. Al-Qaeda particularly will be seen in retrospect as a really profound response to global communications technology."
But al-Qaeda is trapped in the false dichotomy of a clash of civilisations. What we are actually facing is a "clash within civilisations". Moral change cannot be generated if we see the whole issue of global power in terms of the west versus the rest. The "Clint Eastwood versus the bad guys" approach, he says, "only reinforces a dualistic world - 'We're all right: you're all wrong.' The only way America is going to change is through America. The only way Jews are going to change is through Jews. That is the tough fight. The clash between civilisations is easy. It's settled by power in the long run. A clash within civilisations is difficult and it is settled by the force of ideas." Does he think al-Qaeda has it wrong in the sense that it does not realise that the US can be changed only from within? "I don't know that al-Qaeda is trying to change America, only that it is trying to get it out of certain regions. I don't think Osama Bin Laden is trying to convert George Bush. I think he's saying, 'Would you please get out of Saudi Arabia?'"
The Chief Rabbi's own ideas have often led him into deep waters. In the first edition of The Dignity of Difference he suggested that the monotheistic faiths should give up all claim to exclusive notions of Truth, as this leads to an aspiration to conquer or convert the world. The demands of a pluralistic world require each religion to see its truth as partial and individual. He was attacked from all sides - and quite taken aback by the reaction. The book came out at a "tempestuous time", he recalls. Has he, I wonder, been forced to change his position? "No!" he replies emphatically. But he was too far ahead of his congregation. "A leader must not be so far ahead that when he looks back, nobody is following." Judaism, he argues, "has classically had this notion of the universal and the particular. You don't have to be Jewish to get to heaven. What I said in Dignity of Difference is not what I think is controversial. I just said it rather sharply and poetically." So why the retreat in the second edition? It was not a retreat, he insists, but "a softening of the language", a way of saying "the same thing in a slightly more traditional way".
His ideas on 20th-century history would seem equally blasphemous to many Jews. Too much emphasis is given to the Holocaust: "It can be terribly self-destructive." That is why Holocaust Memorial Day has to be opened up. We have to say "this is not the only tragedy", Dr Sacks insists. There are other tragedies we must remember: Bosnia, Rwanda, Cambodia.
Israel must also face this reality. The Zionist principle of Greater Israel has already been brought crashing down by the force of the reality principle. Israel is exhausted, its society so profoundly divided that he feared a civil war. "Religious/secular, Ashkenazi/Sephardi, the fairly wealthy urban elite and the very poor": these divisions have not been dealt with, and there has to be a "mending process" that "hasn't been fully addressed since the birth of the state".
Does he envisage a viable Palestinian state? "Yes, I hope so, but the question is, who is going to be the leader that will bring the reality principle to bear?" He thinks Israelis have realised, with the election of Hamas, that unilateral withdrawal from the occupied territories is necessary. Today's terrorists can become tomorrow's peace activists. "I have certainly sat with a former Hamas terrorist who became a peace activist," he says. The task of Israeli political leaders is to educate the public to face these facts. The two sides need "a fair divorce with a fair settlement".
Israelis and Palestinians would come together, he insists, because of "our shared tears". During a recent visit to Israel, he came across Israeli and Palestinian par-ents who had lost their children. "What brought them together was that they did not want others to go through what they had. It seems to me that if there is one people that can understand Palestinian tears better than most, it is the Jewish people."