George Passion has written on many aspects of modern religious thought and philosophy. From 1994-98, he was editor of "Modern Believing", and has also written and broadcast on religion and the arts. His books include "Art, Modernity and Faith", "Agnosis: Theology in the Void" and "Kierkegaard and the Crisis of Faith".

Existentialism was one of the most important influences on twentieth-century thought, especially in the period between the 1920s and early 1960s. Best known in its atheistic representatives such as Sartre, it also numbered many significant religious thinkers. Anxious Angels is a critical introduction to these religious existentialists, who are treated as a coherent group in their own right and not merely derivative of secular existentialism. The book argues that they constitute a distinctive religious voice that continues to merit attention in an era of postmodernity.