In this book, Roger Mitchell traces what he calls the fall of the church right back to its legitimation by the Roman Empire in 300.
Describing what he calls the "subsuming of the transcendent by sovereignty" (or God's agenda being taken over by the world's agenda) Mitchell traces the ways in which the church through the ages has chosen power rather than the way of love. This manifests through the Crusades, the Inquisition, the murder of the Anabaptists during the Reformation, right through to the tele-evangelists and the religious patriotism of today.
The key to all of this is learning to die to ourselves and follow the Way of Jesus, that is through self-emptying and living for the sake of others.
This is a rather difficult book to read as Mitchell is an academic, but it is worth the effort for everyone struggling with how to engage the gospel in our culture.