A highly regarded historian and professor presents a sustained reflection on the meaning of the Church's life in time. Divided into five parts, each section takes up a period of Church history and considers how the developments in church history relate to the Church today. From doctrines to customs, Olsen examines both the theological and historical impact of each new development.

Beginning with ancient Christianity, the author illustrates how both secularization and sacralization take place in history and how it corresponds to our own age. Taking the reader from late ancient and early medieval Christianity, to the full bloom of medieval scholasticism and scholarship, to the dawn of the Renaissance and the aggressively anti-religious time of the "Enlightenment", Olsen considers all aspects of every age. The final section is a discussion of the Church in our own time, confronting such problems as modernization and the relation of the Church to culture. Appendices expand on The Catechism of the Catholic Church's teaching on the relation between prayer and history.