The Pilgrim's Progress by John Bunyan

Every person who has ever felt crushed by the weight of their failures, paralysed by fear or lost in the Slough of Despond will recognise themselves in Christian. Bunyan wrote this extraordinary allegory in prison and it carries the unmistakable authority of someone who had sat in the darkness himself. The journey from the City of Destruction to the Celestial City is not a straight line. It passes through doubt, temptation, imprisonment and grief. But it ends in glory. For any reader who wonders whether they will ever reach the other side of their hardest season, Christian has already walked that road and left the path marked.