I saw the film "1917" on the vigil of the feast of the Baptism of the Lord, and I think there's a connection between the movie and the liturgical celebration. Bear with me.

First, as everyone who has seen it remarks, the editing and cinematography of "1917" are so astounding that it appears to unfold completely in real time, the result of one continuous shot. Think of the famous scene from Scorsese's "Goodfellas," in which Ray Liotta and his date walk into the night club -- but now stretched out for two hours. What this produces in the viewer is an almost unprecedented sense of being there, experiencing the events with the characters in the film. And to be inserted into the First World War is, to put it mildly, horrific. Obviously, all wars are terrible, but there was just something uniquely appalling about World War I: the oppressiveness of the trenches, the rampant disease, the hopelessness of fighting over a few hundred yards of blasted earth, the rats (which play a prominent and disgusting role in "1917"), and above all, the mass killing that was the result of combining antiquated military strategy and modern weaponry. As witnessed to by so many thinkers and writers who participated in it -- Paul Tillich, J.R.R. Tolkien, Ludwig Wittgenstein, Ernest Hemingway, etc. -- the First World War represented, as did no other war to that date, a collapse, a sea change, a cultural calamity.

And a principal reason for the disaster of the War, too often overlooked in my judgment, is spiritual in nature. Almost all of the combatants in the First World War were Christians. For five awful years, an orgy of violence broke out among baptized people -- English, French, Canadian, American, Russian, and Belgian Christians slaughtering German, Austrian, Hungarian, and Bulgarian Christians. And this butchery took place on a scale that still staggers us. The fifty-eight thousand American dead in the entire course of the Vietnam War would be practically a weekend's work during the worst days of World War I. If we add up the military and civilian deaths accumulated during the War, we come up, conservatively, with a figure of around forty million. And what precisely were they fighting for? I would challenge all but the most specialist historians of the period to tell me. Whatever it was, can anyone honestly say it was worth the deaths of forty million people? Mind you, I am not advocating pacifism. But I am indeed invoking the Church's just war principles, one of which is proportionality -- that is, that there must be a proportion between the goods attained by the war and the cost involved in achieving those goods if the war is to qualify as justified. Did such a proportionality obtain between means and ends in regard to World War I? I think the question sadly answers itself.

My point, again, is that this moral catastrophe unfolded in the heart of Christian Europe, almost exclusively among baptized people, all presumably schooled in the moral principles of Jesus Christ. How many Christians of that time raised their voices in protest, refused to cooperate with the folly of the war, placed their religious identities above their ethnic or national identities? Those questions, too, answer themselves -- which brings me to the Feast of the Baptism of the Lord. According to the theology of the Church, Baptism involves the grafting of a person on to the Son of God, implying a share in the relationship between the Son and the Father in the unity of the Holy Spirit. It is infinitely more than the joining of a club or society; it is a participation in the inner life of God. Another way to put it is this: Baptism inserts a person into the Mystical Body of Jesus, which is an organism rather than an organization. Therefore, all of the baptized, despite even dramatic differences at the cultural, political, or ethnic levels, are related to one another, implicated in each other, like cells and organs in a body. To forget this truth, or even to underplay it, is to lose what it means to be a Christian.

For the past many years, I have been studying the phenomenon of disaffiliation and loss of faith in the cultures of the West. And following the prompts of many great scholars, I have identified a number of developments at the intellectual level -- from the late Middle Ages through the Enlightenment to postmodernism -- that have contributed to this decline. But I have long maintained -- and the film"1917" brought it vividly back to mind -- that one of the causes of the collapse of religion in Europe, and increasingly in the West generally, was the moral disaster of the First World War, which was essentially a crisis of Christian identity. Something broke in the Christian culture, and we've never recovered from it. If their Baptism meant so little to scores of millions of combatants in that terrible war, then what, finally, was the point of Christianity? And if it makes no concrete difference, then why not just leave it behind and move on?

I wonder whether we might take the Feast of the Baptism of the Lord as an opportunity to think more deeply about the moral implications of being a son or daughter of God, and hence a sibling to everyone else in the Mystical Body of Jesus. And I wonder whether we might look long and hard at this wonderful and disturbing film in order to see what happens when Christians forget who they are.

- Bishop Robert Barron is the founder of the global ministry, Word on Fire, and is an Auxiliary Bishop in the Archdiocese of Los Angeles.