The New Testament calls Christians doulos, and the word means slave, not servant. MacArthur's case is that English translators have consistently softened it, and that the softening has cost readers something central: an identity defined by belonging wholly to another, bought at a price, owing absolute allegiance and receiving absolute protection. He traces the word through the apostles' own self-descriptions.

The book sets the term in the context of first-century slavery as it actually was, then draws out what the metaphor was chosen to convey about redemption, obedience and security in Christ. It includes a study guide for personal or group use. The framing is deliberately provocative, and the underlying lexical point is one most readers have never had explained.