"Those standing in the stream of historic Christianity have been especially slow to understand the relationships between various areas of thought. When the apostle warned us to "keep [ourselves] unspotted from the world," he was not talking of some abstraction. If the Christian is to apply this injunction to himself he must understand what confronts him antagonistically in his own moment of history. Otherwise he simply becomes a useless museum piece and not a living warrior for Jesus Christ."
- Francis Schaeffer in The God Who Is There.