By Robert Royal.

Most Christians - though far from all, in the current decay of education of all kinds, including religious education - know that the events we commemorate this week have had the most wide-ranging effects of anything that has happened in the entire history of the human race. And beyond, into the next world. Anyone, Christian or not, who looks back in time without a jaundiced eye, has to recognize that the Christian revolution has touched virtually everything. And that this has been a blessing as well as - not a curse, but an obstacle, in more recent times to appreciating just how great a change God-become-man introduced into the world.

Because when people assume they know the plot and the outcome of the Christian story, they take it for granted, as something that's just the everyday background. They believe that it has existed always and everywhere. And that whatever is good in it has already been integrated into human life and doesn't need particular attention any longer. Tom Holland, a "cultural Christian" and (probably, though he seems to be wavering) not a believer, traces this whole process in his remarkable book Dominion: How the Christian Revolution Remade the World. Without Christ: no acknowledgment of human freedom or dignity, no transcendence of the merely political, no spread of Jewish monotheism (nor the Christian heresy we call Islam), no end to slavery, no respect towards women, ad infinitum.

By the end, Holland identifies so many things in our world with origins in Christianity that you almost want to pull him up short and ask, "Wait a minute, friend, aren't there things we value that have come from outside the Christian tradition?"

My wife and I have been watching (parva cum magnis comparare) an intriguing BBC series, "SS-GB," based on a novel by Len Deighton, which imagines a counter-historical scenario: What if the RAF had lost the air battle over Britain and the Nazis had taken over England? A police detective finds himself in a dilemma, having to fight crimes and, at the same time, work with the Nazi SS, in the hope that he can learn things that will help undermine and ultimately expel the invaders.

It may seem a stretch, but if you look around the world at the evils that beset us on every side - or even look into your own heart and actions - it's clear that we're occupied by some alien force. The Devil is the father of lies, but when he shows Jesus the kingdoms of the world and tempts Him, "All this power will I give you, and the glory of them: for that is delivered to me; and to whomsoever I will I give it" (Luke.4:6), it doesn't seem entirely implausible.

When I first read C. S. Lewis' Chronicles of Narnia to my children, I balked a bit when he would describe Aslan (a lion symbolizing Christ) as "having landed" and being "on the move" with his followers. Like everything Lewis wrote, it was a lively image, but seemed too simplistic to me. Now I realize, I was the simpleton. Lewis - and Tolkien - experienced both world wars and the air battle over Britain. They both knew in their bones, and brilliantly embodied in their books, a sense of the spiritual combat going on in our world - and will be with us until the end of the age.

The spiritual battle ought to be more evident to us now, rather than less. But the Evil One has his dark arts and has been very successful in diverting our attention from the main theater of combat to lesser ones. Most people think our evils are just a series of clashes over politics, economics, sex, power, and other evanescent goals.

When St. Anselm wrote Cur Deus Homo? - "Why Did God Become Man?" - around 1099, he, along with much of the Middles Ages, was curious about a different, but related question. In theological perspective, the Incarnation is a "mystery." But Faith and Reason are, as St. John Paul II reminded us, two wings by which the human spirit rises to God. Reason cannot entirely explain the revealed mysteries - which is why truths like the Trinity a...