What happens when authorities you venerate condone something you know is wrong? Are you right or are they, and what does this mean about what you've been venerating? No issue brings this question into starker contrast than slavery. Every major religion and philosophy condoned or approved of it, but in modern times there is nothing seen as more evil. Americans confront this crisis of authority when they erect statues of Founding Fathers who slept with their slaves. And Muslims faced it when ISIS revived sex-slavery, justifying it with verses from the Quran and the practice of Muhammad. This book explores the moral and ultimately theological problem of slavery, tracing how the Christian, Jewish and Islamic traditions have tried to reconcile modern moral certainties with the infallibility of God's message, in particular on the issue of sex-slavery. It investigates the challenge of defining what slavery is in the first place, showing that this remains more than ever a highly politicized question. This book lays out how Islam viewed slavery in theory, and also how slavery was practiced across the reality of Islamic civilization. Finally, it explains how Muslims have argued for the abolition of slavery in Islam, asking whether their arguments are sincere and convincing.