It's Christmas lunch at my house this year. My mother, a practising Jew, will be at the table, and so will my father-in-law, a fundamentalist Christian. My children were bequeathed a rich religious heritage but they have turned out to be "none": non-scripture, non-believers, non-religious. Before they were 13, they were declared atheists. "C'mon, Mum, how can we have a bar-mitzvah if we don't believe in God?" they intoned. And the idea of going to church on Sunday instead of to soccer struck them as ludicrous. If they had a religion, it was sport. People with religious or spiritual beliefs...