Here is what looks like a very useful (although quite expensive) introduction to the subject of political theology: The Wiley Blackwell Companion to Political Theology (Wiley Blackwell, 2d edition), edited by William T. Cavanaugh and Peter Manley Scott.

“This book presents the latest thinking on the topic of contemporary Christian political theology, with original and constructive essays that represent a range of opinions on various topics. With contributions from expert scholars in the field, it reflects a broad range of methodologies, ecclesial traditions, and geographic and social locations, and provides a sense of the diversity of political theologies. It also addresses the primary resources of the Christian tradition, which theologians draw on when constructing political theologies, and surveys some of the most important figures and movements in political theology. This revised and expanded edition provides the most comprehensive and accessible introduction to this lively and growing area of Christian theology.

Organized into five sections, Wiley Blackwell Companion to Political Theology, Second Edition addresses the many changes that have occurred over the last 15 years within the field of political theology. It features new essays that address social developments and movements, such as Anglican Social Thought, John Milbank, Anabaptist Political Theologies, African Political Theologies, Postcolonialism, Political Economy, Technology and Virtuality, and Grass-roots Movements. The book also includes a new essay on the reception of Liberation Theology.”