What key work did John Calvin write that significantly influenced Protestant theology?

John Calvin's "The Institutes of the Christian Religion" is a foundational text for Protestant theology that outlines his understanding of the Christian faith and systematic theology. First published in 1536 and expanded in subsequent editions, this work articulates key doctrinal points such as the sovereignty of God, the nature of sin, and the significance of grace.

Calvin's method of presenting Christian doctrine in a clear and organized format allowed for a deeper understanding of theological concepts, making it accessible to those seeking to learn about Protestant beliefs. His emphasis on scripture as the central source of authority for believers and the concept of predestination are particularly influential aspects of his teaching. The text not only served as a guide for personal faith but also shaped the practices and beliefs of Reformed churches across Europe, solidifying Calvin's role as a principal figure in the Protestant Reformation.

In contrast, "The Imitation of Christ," while important in Christian spirituality, comes from Thomas à Kempis and does not hold the same theological weight within the framework of Protestantism. "The Book of Common Order" and "The Book of Discipline" pertain to different aspects of church governance and worship practice, reflecting the structure and regulations of specific faith communities rather than outlining broad theological principles as Calvin