As September 11^th approaches, Americans remember the morning in 2001 when the World Trade Center turned to rubble. It is a fitting time to consider the nature of the civilizations that collided that day—and how to defend ours.

In their quest to establish a worldwide caliphate, radical Islamists invoke morality, claiming they have God’s sanction for performing their barbarous acts.

To defend Western civilization, we, also, need to invoke morality. But although the world envies the wealth we’ve achieved, it is widely seen as the product of soulless materialism, of unbridled “greed,” of unscrupulous self-indulgence.