In the 1990s, Americans—evangelicals included—were beguiled by grand utopian illusions. Basking in prosperity, we assumed our 401Ks would keep us fabulously wealthy. One scholar, Francis Fukuyama, famously wrote that we had arrived at The End of History; Western liberal democracy had won the great ideological struggle of the 20th century. Some interpreted this to mean that, with America the only remaining superpower, peace and prosperity were assured.

Those visions lie in the twisted wreckage of September 11.

The most accurate prophet of the '90s, it turns out, was Harvard's Samuel Huntington, who warned of a clash of civilizations in the 21st century, divided along historic religious boundaries—the Christian West, the Confucian East, and Islam's scattered nations.

The attacks proved Huntington right. Great clashes of worldview—that is, how people understand ultimate reality—continue to divide the world, and will do so until the true end of history when the Lord returns.

More than ever, Christians must be aware of new battle lines in the struggle of worldviews. The terrorist attacks delivered a body blow to postmodernism. Can anyone who saw the incineration of thousands of innocent Americans believe, as postmodernists teach, that there is no objective reality, no good or evil, or that all cultures are morally equivalent?

At the same time, the attacks sharpened the lines between extreme Islam and the Christian West, which were drawn in blood 13 centuries ago. Islam is not a monolith, and even now Muslims are struggling afresh to define it; but on key points it radically differs from Christianity.

Islam's worldview sees God as remote, utterly transcendent. Christians worship a God who became flesh and intimately knowable and personal ...