On consecutive Wednesdays this month (Sept. 15 and 22), PBS stations will be airing a two-part documentary, The Question of God: Sigmund Freud and C.S. Lewis. It’s a study in contrasts between two of the most influential men of the 20th century: the atheist Sigmund Freud, who held that all human affairs could be explained by secular psychoanalysis, and the ex-atheist Lewis, who became the most popular Christian writer of his era and beyond.

Recently I saw a one-hour preview of the four-hour special. Based on what I saw, I have to say, not everyone will be fascinated by every minute of it; it includes a fair amount of debate among academic types that many viewers may find heavy going. But at the heart of the show are compelling segments from the lives of both Freud and Lewis (including actors’ re-creations) that demonstrate the stark difference between life with God and life without Him.

The two men actually had their similarities. Both suffered blows to his faith early in life: the Jewish Freud when his family fell into sudden poverty, the Christian Lewis when his mother died and his father withdrew into often-tempestuous grief. Both emphasized the value of reason, though Lewis (unlike Freud) recognized its limits.

And above all, both agreed on the importance of their disagreements. As Harvard Professor Armand Nicholi (who teaches a course on which the documentary was based) says,

Are these worldviews merely philosophical speculations with no right or wrong answer? No. One of them begins with the basic premise that God does not exist, the other with the premise that He does. They are, therefore, mutually exclusive — if one is right, the other must be wrong. Does it really make any difference to know which one is which? Both Freud and Lewis thought so. They spent a good portion of their lives exploring these issues, repeatedly asking the question, “Is it true?”

No “you-have-your-truth-I-have-my-truth” wimpiness for these men; no “all that matters is that you have beliefs which have meaning for you” cop-outs. It made all the difference in the world who was right and who was wrong, and both of them knew it. In the words of the Apostle Paul, if the Christian faith is not true, then believers “are to be pitied more than all men” (I Corinthians 15:19).

Thus, Freud practiced a kind of intellectual consistency in his disdain for Christian belief. To Freud, all religions were not only untrue, they were, literally, sick. “Religion is the universal obsessional neurosis of humanity,” he said — a reflection of a childish desire for parental protection and consolation. To Lewis, the fact that religious belief was so widespread reflected a longing built into human beings by their Creator. To Freud, the recurring themes of myths found throughout many cultures (expulsion from paradise, immortality, sacrifice, resurrection) were explainable as signs of a kind of racial memory of emotional episodes, rooted in human desires; to Lewis, they were signs of the true God, Who was known on some level even by those who had not heard (or had rejected) His Word.

There isn’t room to get into all the arguments of the two men. (Though you can find samples — in their own words. ) But important as they are, the arguments aren’t really the most striking part of the documentary. What’s most interesting is the kind of man each became as a result of his beliefs.

Freud was said to be a devoted family man, though he could be stern. (He forbade his devoutly Jewish wife to practice her faith in the home.) But he never could truly understand what love was; he saw it as nothing more than an essentially selfish desire which goes in search of satisfaction by another person. Lewis had a dramatically different, and much broader, view. As Yale theologian Gilbert I. Bond put it in the documentary,

Lewis is differentiating between the different kinds of love that all human beings have, and identifying that it is natural to love one’s brother, one’s family members, enter into relationships with friends, male and female, enter into romantic and erotic love. But he also recognized this mysterious realm of love that did not have a direct and immediate personal benefit, and he identified that as agape, or a selfless love, a love that was committed to the well being of the other. And passionately so.

This wasn’t just theory to Lewis. It was a reality in his own life, moving him toward joyful service to other people. The PBS special provides testimony to that. “When he converted, he lost all interest in himself,” says his former secretary and biographer Walter Hooper. “I can’t underscore that enough — what a change that was in that man.” And lots of people noticed. “He became, as his friends saw, very selfless and looked outside of himself,” says James Como of the New York C.S. Lewis Society. That was a kind of outlook that Freud could not know.

The spiritual difference between Freud and Lewis may best be seen in their response to tragedy.

Freud refused to consider a deeper meaning to life even in times of greatest sorrow, like the death of his daughter in childbirth and (shortly afterward) the death of her 4-year-old son. He could take no consolation, nor even get angry at God. “As the deepest of unbelievers,” he said, “I have no one to accuse.” His denial of God’s existence — his insistence on seeing nothing greater than man in the universe — carried through right up to his own long, painful death from throat cancer, which he short-circuited with an overdose of morphine. He died “as he had lived,” says an admirer in the film, Freudian psychiatrist Ana-Maria Rizzuto, “with this kind of rebellious defiance and conqueror stance.” The sadness of that supposed “conquest” testifies as powerfully as anything in the film to the ultimate hollowness of Freud’s view.

Lewis, even in his darkest moments, retained a far healthier view. When his wife died after a bout with cancer, he raged at God; unlike Freud, he did have Someone to accuse. He even grappled with the fear not that God doesn’t exist, but that He is a cruel tormenter. Yet in Lewis’ Job-like reaction, as Boston college professor Peter Kreeft says, “it’s a deep trust in God that allows him to give vent to his distrust.”

And ultimately, his rage spent, Lewis repentantly turned once more to trust in God. He reflected on how selfish he had been, to want to keep his wife by his side at all costs rather than in the eternal and boundless joy to be found with her Maker. “How wicked it would be if we could call the dead back,” he reflected. Of his wife’s final hours, he recalled,

She said, not to me, but to the chaplain, “I am at peace with God.” She smiled. But not at me.

In moments like that, even the most secular viewers may sense a calling to the longings of their souls beyond what they could ever expect or explain away. It’s not likely most of us will ever know what comes of that. But we may trust that in this, as in all things, God will be at work.