Book excerpt: Recent decades have seen major shifts in our understanding of Christian identity. This timely book explores contemporary theological theory in asking what makes a Christian in the twenty-first century. Engages with developments in contemporary theological thought, assessing the work of leading figures Rowan Williams, John Milbank, and Kathryn Tanner Challenges accepted ideas of Christian identity by revealing largely unexplored perspectives on how sin affects its formation Contributes to vexed debates about Christian identity at a time when Christianity is expanding in some regions, yet in decline in many parts of the Western world