The Chief Rabbi Lord Sacks says he has put his faith "on the line" for his annual Rosh Hashanah broadcast this year when it goes out on BBC1 onSunday night.
Entitled The Case for God? the programme features him in conversation with four of Britain's "cleverest" critics of religion - as he calls them.
Three are Jewish - Howard Jacobson, Alain de Botton and Lisa Jardine. The fourth, neurobiologist Colin Blakemore, argues that science has made religion irrelevant.
At one point, the Chief Rabbi is asked by Howard Jacobson whether he is sure there is a God.
Pausing, the Chief Rabbi replies: "You know, I believe that faith isn't certainty. Faith is the courage to live with uncertainty.
"Judaism is a refusal to give way to despair. And that's why I stake my life on the hope that the call God gave us at the beginning of history was the call worth following."
When the Booker-listed novelist expresses his distaste for the minutiae of ritual, Lord Sacks answers that "God is in the details".
Which elicits the riposte from Mr Jacobson: "The devil is in the detail, Chief Rabbi."