Anthropology -- the understanding of human nature - is a vital aspect of the Christian faith. Christians affirm that human beings are made 'in the image of God'. We are, each and every one us, of infinite worth, made for life in relationship with God and with each other. But what does that affirmation mean today? How can Christians confront todays challenges to traditional understandings of human nature, and respond to the widespread assaults on human dignity and worth? This book is the result of a wide-ranging study by the commission on Faith and Order of the World Council of Churches. It brings Christian understandings of the human person into critical conversation with cutting-edge issues from genetic engineering and artificial intelligence, to poverty and HIV/AIDS, to disabilities and gender identity. The book culminates with Ten Affirmations on Human Nature, offered as a basis for common reflection and action. It will be a valuable resource for Christians and churches seeking to understand -- and defend -- the human person in todays complex and changing world.