Here's a taste:
"Ellul's basic thesis is that the Kingdom Jesus inaugurated with his life, death and resurrection has been subverted -- converted into its opposite, in fact -- in the religion of Christendom. This happened primarily because leaders in the 4th and 5th century decided to give into the temptation that Jesus resisted (Lk 4:5-7) -- namely, acquiring political power (thus, submitting to the devil's authority). Christianity thus was co-opted by "the powers." A movement that was in its very essence non-conformist became a religion of conformity. Indeed, Christianity has historically usually been a defender of the status quo ("conservative")."