In 1997 I published a book called The Politics of Hope, in which I argued that the world had moved on since Berlin's great 1957 lecture "Two Concepts of Liberty", and that the threat to liberty was now different: not totalitarianism but rather the internal moral decay of free societies. I asked him if he would be kind enough to take a look at the book, because I was keen to know his response. He told me to send him the book and he would let me know his thoughts. The months passed and I heard nothing, so I telephoned Headington House. Lady Berlin answered the phone and said, "Chief Rabbi, Isaiah's just been talking about you." Rabbis were not the usual subject of Isaiah Berlin's conversations, so I asked in what context he had mentioned me, and she said, "Isaiah has just asked you to officiate at his funeral." Clearly Isaiah knew. Four days later he died and I officiated at his funeral. His biographer, Michael Ignatieff, asked me why Isaiah, a secular Jew, wanted a religious funeral. I said — I hope I didn't get it wrong — that  Isaiah may have been a secular Jew but he was a loyal Jew. So I felt a strong kinship with him, even though his religious views were different from mine.

This sense of kinship across intellectual divides is the Jewish equivalent of the lovely English idea of "dining with the opposition"  — the ability to sustain personal friendships even when our views are opposed. That human bond is lost when scientists and religious leaders hurl abuse at one another, vilifying and misrepresenting each other's views. That cannot be good for religion or for science or for the future of the humanity we share.

So I return finally to where I began, with Robert Putnam. Putnam argued in his book American Grace, that what makes the difference to people, turning them into good citizens and good neighbours, is belonging to a community, rather than what people believe. He wrote that an atheist who goes regularly to synagogue or to church is likely to be a better human being than a religious believer who never joins a community.

In a surprising way the rabbis suggested something similar. A famous rabbinic text has God saying, "Would that they disbelieved in Me but studied My Torah. For if they study My Torah, its light will bring them back to Me." That is a very radical statement, and it is a basis on which believer and non-believer can join hands in friendship. The sociologist of religion Grace Davie said about English Christianity that it consists of believing without belonging. The Jewish community tends to be the opposite: belonging without necessarily believing. We now know, courtesy of Robert Putnam, that it is the belonging that makes the difference.

I once defined faith as the redemption of solitude. It sanctifies relationships, builds communities, and turns our gaze outward from self to other, giving emotional resonance to altruism and energising the better angels of our nature. These are some of the gifts of our encounter with transcendence, and whether it is love of humanity that leads to the love of God or the other way round, it remains the necessary gravitational force that keeps us, each, from spinning off into independent orbits, binding us instead into the myriad forms of collective beatitude. A society without faith is like one without art, music, beauty or grace, and no society without faith can endure for long.