The Dove, the Fig-Leaf and the Sword: Why Christianity changes its mind about war

Why does the pacifist movement of the first few centuries so quickly become an organization that supports emperors and finds reasons for fighting? ? What leads the Church to formulate just war principles only to abandon them when in pursuit of heretics and infidels? ? What impact did two world wars have on Christian thinking? ? Why have the churches in more recent years and a more secular age apparently taken a more cautious approach to war? These are the sort of questions this absorbing bo...