"Pagan Christianity? Exploring the Roots of our Church Practices" by Frank Viola and George Barna (2008)
From the inside cover,
"Many Christians take for granted that their church's practices are rooted in Scripture. Yet those practices look very different from those of the first-century church. The New Testament is not silent on how the early church freely expressed the reality of Christ's indwelling in ways that rocked the first-century world.
Times have changed. Pagan Christianity? leads us on a fascinating tour through church history, revealing this startling and unsettling truth: Many cherished church traditions embraced today originated not out of the New Testament but out of pagan practices. One of the most troubling outcomes has been the effect on average believers: turning them from living expressions of Christ's glory and power to passive observers. If you want to see the trend reversed, turn to Pagan Christianity?....a book that examines and challenges every aspect of our present-day church experience."