Gavin Ortlund’s "What It Means to Be Protestant" presents a defense of "mere Protestantism," framing it not as a novel departure but as a historical retrieval of the apostolic gospel. The book argues that the Reformation was a necessary renewal movement aimed at removing medieval accretions, such as indulgences and the centralization of papal power. Ortlund advocates for sola Scriptura and sola fide, contending that these doctrines provide a clearer sense of assurance and clarity regarding salvation. He challenges the institutional exclusivism of Roman Catholic and Eastern Orthodox traditions, suggesting that the true church is found wherever Christ is present in word and sacrament. Throughout the text, the author emphasizes convicted civility, urging readers to engage with church history and opposing traditions with humility and intellectual honesty. Ultimately, the work serves as an apologetic for the always-reforming church, focusing on the simplicity and sufficiency of Jesus Christ.