What do Muhammad Ali, Helen Shapiro and John Travolta have in common? They all changed their religion. They abandoned the traditions in which they had been brought up in favour of something different. In some cases, it produced a great sense of betrayal. Some religious groups will cut off friends and family who renounce their religion. Life for the so-called betrayer can be very difficult indeed. The idea of betrayal runs very deep in many religions. Why? And what does it actually signify?

Ernie Rea is joined by Prakash Shah, Director of the Centre for Culture and Law at Queen Mary, University of London; Rabbi Dr Naftali Brawar, Chief Executive of the Spiritual Capital Foundation Think Tank; and Douglas Davies, Professor in the Study of Religion at Durham University.

Produced by Nija Dalal-Small.