My first introduction to the 'theology' of U2 and its applicability to modern worship contexts came from the book 'Get Up Off Your Knees : Preaching the U2 Catalog' by Raewynne J. Whiteley. This book is addresses some of the same material, and is a good companion to Whiteley's book.
Vagacs makes the apt point that music of U2's sort is the poetry of the modern age. Adults young and old don't tend to learn poetry, but they do remember song lyrics, and many of these song lyrics contain deep, meaningful, spiritual content. Vagacs taps into the categories of biblical interpretation and meaning-making of Walter Brueggemann (one of my personal favourites), and looks to the medium of modern rock and roll ('potent poetry' that 'allows the artist to express raw emotion and high intellect simultaneously') to be a means toward an 'alternative universe of discourse'.
It isn't simply in the lyrics of U2 songs that the call to fulfilling a moral purpose, a gospel statement if you will, comes into being. Bono has taken upon himself the task of educating and drawing the media spotlights to issues of world poverty, hunger, and financial mismanagement that is a somewhat ironic stance for a 'pop star'. However, no one else seemed to be stepping up to the plate. Bono was honoured with the Bill and Melinda Gates by Time magazine, not for fame and fortune, but rather for turning fame and fortune into a force for good in a specific, savvy and increasingly effective way.
There are elements in U2 songs that all Christians can find familiar - hope and despair, faith and doubt, longing and desire, dealing with injustice and finally finding grace. All of these things, from lamentations to psalms and proverbs, have parallels in both biblical and U2 lyrical words. Vagacs deals with the idea of the postmodern (an idea he admits is difficult to define, particularly in so short a work), and demonstrates in many ways that U2 is a postmodern embodiment of many biblical themes.
Vagacs includes a litany inspired by U2 lyrics, merged with themes and words from the gospel of Mark. Vagacs also includes a discography, source lists, and a recommended readings list. These are handy things for those who might want to further their study, or incorporate U2 into actual worship services.
Vagacs includes a glossary of terms at the start, rather than at the end. This is both for U2 fans who are not theologically/philosophically trained, as well as for those theological types who don't have a wide exposure to modern popular/rock music. Vagacs states, 'My hope is that this book will be of interest to U2 fans, offering them perhaps another perspective on U2's lyrics. I would also hope that those who are Christian, or religious, would recognize that the marriage of theology, faith and popular culture is not only possible, but relevant and fruitful as well.'