The Reformation — Diarmaid MacCulloch

MacCulloch's history of the Reformation is the standard work — comprehensive, richly detailed, and written with the conviction that ideas matter as much as interests. He covers the full range of Protestant movements, from Luther's German reformation through Calvin's Geneva to the English break with Rome, while also taking the Catholic response seriously as a genuine reforming force rather than mere reaction. The sheer scope is managed without sacrificing the texture of individual argument and conflict.