Before the trip Darwin had been 'a sort of Christian': 'orthodox' in a conventional, rational, Anglican kind of way. What he experienced on the Beagle set him on a journey from Christianity, through theism, to the muddled agnosticism of his old age.

Nick Spencer draws on Darwin's autobiography, manuscripts, notebooks and letters - as well as his world-famous publications - in exploring Darwin's view of design, purpose, morality, the universe and the human mind. The author argues that, although Darwin's theory of evolution by natural selection did undermine his Christian convictions, it was the age-old problem of suffering - first in theory, then through the dreadful loss of his favourite child - that caused his faith to break down.