There are many ways to study theology -- topically, by denominational structure, by particular theologians, etc. One of the more common approaches, and still a popular one, has been to study theology through the historical development of ideas, beliefs and doctrines. Alister McGrath's book, 'Historical Theology: An Introduction to the History of Christian Thought' is one such text. Following a brief introduction, it is divided into four broad historical sections: The Patristic Period (100 - 451), the Middle Ages and Renaissance (500 - 1500), the Reformation and Post-Reformation (1500 - 1750), and finally, the Modern Period (1750 - the present).
In his introduction, McGrath traces the various sources and types of theology - biblical studies, philosophy, pastoral issues, and church history all provide insights into this. The development of historical theology as a discipline began in the Reformation era, when it became important to understand not only the doctrines and dogmatic principles of the church, but also how they came to be developed and instituted. Historical theology is an important pedagogic and critical tool, useful for creating a greater understanding of our present situations.
McGrath's chapters on the Patristic and Middle Ages periods look at the wider church ideas, developments of the creeds, canon of scripture, and early ecclesial structures along with the development of key ideas and key theologians. In addition to this, McGrath presents case studies, which include the various historical heresies (Donatism, Pelagianism, etc.) and various philosophical problems (arguments for the existence of God). Included here are discussions of the impact of Celtic Christianity and monastic institutions on the overall development of theology.
After these periods, into the Renaissance, Reformation, Post-Reformation and Modern periods, the book is predominantly Western in outlook. Beginning with Scholasticism and the philosophical Humanism of the Renaissance beginning to influence general intellectual life inside and outside of the church, McGrath continues with the various Reformations (not all were the same), including the Catholic Reformation (often termed the Counter-Reformation). The influence of the Enlightenment and theological movements since then include a long list of -isms, including Feminism, Marxism, Modernism and Postmodernism, Postliberalism, Romanticism, Liberal Protestantism, and Evangelicalism (among others!). Case studies in these include the key controversies of ideas in the Reformation, quests for the Historical Jesus, political influences in the theological debates, and the growing influence of the two-thirds world on the theological scene.
McGrath's final case study is on the issue of method in theology in the modern period -- the starting point as well as the purpose is continually questioned, and McGrath highlights issues drawing from Schleiermacher, Tillich, Rahner, Barth, Lindbeck and Guttierez. Immediately following this (indeed, this section could be the beginning of another book, a companion to this text), McGrath addresses the issue of 'Where next?' for the student and reader. McGrath includes an extensive list of suggested further readings, divided by period, topic, and other helpful groupings.
McGrath is a good writer and educator -- this book is accessible to most readers, not assuming a great background in history, philosophy or theology; however, the more background one has, the better the experience of reading this book. It is a survey, which means it does not go into great detail, but it does include a fairly thorough introduction to all of the major and many of the side issues of theology through the 2000 years of Christian history.