I highly recommend this book. Brian McLaren is one of the leaders in the "emerging church" movement, and the book was definitely groundbreaking in its interpretation and application of the Bible.
I don't know what the experience of others has been, but as an evangelical, I heard a lot of stuff that boiled the gospel down to "Believe in Jesus, and God will take away all your sins so that when you die, you can go to heaven and be with him forever; now go and tell everyone else about it too."
McLaren takes the Christus Victor understanding of the gospel, and argues that the Kingdom of God as seen by the prophets is not some distant, post-Armageddon experience, but a reality that arrived in the person of Jesus, and spreads from person to person as we choose to live in the reality of the Incarnation.
A quick example that set the first H-bomb off in my head: I've always been taught that Isaiah and Micah, when they saw a time when the nations would gather by the river, beat their swords into plowshares and study war no longer, were seeing a period after Christ had returned, established his kingdom on earth, and was ruling unopposed.
McLaren notes that when Jesus arrived, his message was not that the Kingdom of God was coming, but that it had arrived, in his person. If Isaiah and Micah, and the other prophets, saw a glorious kingdom off in the distance, Jesus was announcing that it could be found now, through faith, in him.
For me, it was a revolutionary thought. Back in college, I had called myself a pacifist mostly because I hated the idea of being called up to fight and risk getting killed if the government felt a need to draft Selective Service registrants. I eventually acknowledged that cowardice, rather than conviction, was driving my stand, and was willing to argue about whether a war was just or not. But if the Kingdom of God has arrived in the person of Christ, then the question of "just war" is no longer a valid one. War itself must be seen as a gross abrogation of the fundamental purposes that God created humanity for, and in direct conflict of the gospel, which seeks reconciliation between God and humanity, and between the different peoples of the earth.
Of course, it's always easier to make war than it is to zealously pursue peace, because war allows the stronger to impose their will upon the weaker, while peace requires becoming weaker and surrendering your will for the good of someone you might not even love. (This is not to say that a Christian cannot join the military and fight in the service of king and country; this is a matter of individual conscience.) As I was discussing with a friend, it's something you can see in how we view the different leaders we've had. FDR and Churchill are well regarded as wartime leaders, but the respect we have for them generally pales in comparison to the awe and reverence we have for Mahatma Gandhi and men like him who stood their ground with unbowed heads and unraised hands when much stronger forces came against them.
"The Secret Message of Jesus" is an excellent book. Bump it up to the top of your list.