On a recent Sunday morning, I attended Mass in Verteillac, a tiny market town in the Dordogne region of southwestern France. By the standards of France, the most de-Christianized of all western European nations, Verteillac's parish church is doing well, thanks to the efforts of its energetic young priest. But on this visit I felt as if I had been catapulted back several centuries. Instead of the handful of worshippers one has come to expect, there was hardly any standing room left in the large sanctuary, and the service lasted almost two hours, due to the seemingly endless line of communicants.

The reason for the spectacular turnout was this: Ton Koopman, the famed Dutch organist and conductor, has a country home nearby. Every summer he organizes a concert series called Itineraire Baroque in the usually vacant Romanesque churches around Verteillac. This Sunday, though, Koopman brought his singers, instrumentalists—and a portable organ—to the regular 11 a.m. service, magnificently embellishing it with elements of Bach's Mass in B minor.

So it wasn't surprising that the locals, plus British, American, Dutch, and German tourists, forewent the pleasure of a Sunday morning tipple in a local pub in order to go to church, a rare activity in contemporary Europe. What was surprising, though, was the Bach-inspired urge to act like real worshipers; they crossed themselves when the name of the Holy Trinity was invoked; they spoke the Apostles' Creed and the Lord's Prayer and received the consecrated host. In other words, the congregation was worshiping, and not just an audience.

"Never before in my life have I seen so many do this in our church," said a very old lady next to me in the pew. "We owe this to Bach, don't we? And to think that he was a Lutheran!" That experience proved to me the verity of Nathan Soderblom's description of Bach's music as the "Fifth Gospel." Actually, Soderblom (1866–1931), the former Lutheran archbishop of Sweden, restricted this observation to Bach's cantatas. But there is mounting evidence that it applies just as surely to other works by this composer. As a native of Leipzig, Bach's town in Germany, I gladly concur with Arthur Peacocke, the English theologian and biologist, that the Holy Spirit himself had written The Art of the Fugue, Bach's intellectually most challenging work, using the master's hand.

I was first made to listen to Bach's motets consciously in Leipzig's Thomaskirche at age four, and I have been fascinated by the missionary power of his work since my childhood. Now many of my friends in France, where I have had a home for more than three decades, seem to be more familiar with our Lutheran order of service than with their own Catholic Mass. One reason for this is that the radio network France Musique on Sunday mornings often broadcasts the Bach cantata written for that day in the church year—though before you are permitted to enjoy it, a musicologist rather pedantically explains its Lutheran liturgical context.

Recently I discussed Bach with a neighbor, an elderly villager, who praised the "healthy fusion of logic and religious emotion" in his music and bemoaned the dearth of this quality in most of the sermons she had ever heard. I downloaded the French translation of the Augsburg Confession of 1530 and gave it to her to read. "Ah!" she exclaimed, "finally here's something that makes sense to me. I can see the link. This is as clear as Bach."

It is clearly a missionary mystery how Bach manages to draw faith to the surface in jaded people who have long buried it in the deepest depth of their souls—buried it under heaps of doubt and cynicism and secular desires. The wonderful German bass-baritone Thomas Quasthoff once confided to a reporter that he was really an agnostic—most of the time. "But when I perform Bach my unbelief ends at once," added this woefully crippled artist who frequently sings the part of Christ in the St. John and St. Matthew Passions.

"You cannot remain a heathen when you sing these works," several of the sailor-suited boys in Leipzig's Thomanerchor—the choir whose Kantor Bach was for twenty-seven years until his death in 1750—insisted when I interviewed them in the days when Leipzig was under Communist rule. But this same sentiment appears to apply not only to those who sing the music, but to many of those who hear his music, to wit, the astounding success of Bach in Japan, of whose population of 127 million only one per cent officially belong to a Christian church.

When I was last in Tokyo a few years ago, local theologians insisted that another eight to ten percent of their fellow countrymen sympathized with this foreign religion. "Many of these have had their first contact with Christianity through the music of Johann Sebastian Bach," said Yoshikazu Tokuzen, then rector of Japan's Lutheran Seminary.

A relentless Bach boom has been sweeping Japan during this period of great religious impoverishment with skyrocketing suicide rates and a seemingly unbridgeable generation gap between the spiritually disoriented youth and their materialistic parents. The driving force behind this boom is organist Masaaki Suzuki, founder and conductor of the Bach Collegium Japan, which has spawned hundreds of similar societies throughout the island nation over the last fifteen years.

During Holy Week, Suzuki's performance of the St. Matthew Passion is inevitably sold out—regardless of how expensive the tickets. Then, as after every one of the Bach Collegium's performances, non-Christian members of the audience crowd Suzuki on the podium questioning him about the Christian concepts of love and hope—and about death, a topic that is taboo in Japanese society. "I am spreading Bach's message, which is a biblical one," said Suzuki, who is convinced that this eighteenth-century composer has already converted tens of thousands of Japanese to Christian faith.

I have always wondered, though, why Bach's western melody and harmony should have such a profound effect on an alien culture. During my many years in that part of the world I often listened to Asian music and found it exotic, at times aesthetically pleasing. But did it move me? No. Did it turn me into a Buddhist, a Hindu, or a follower of Shinto? Definitely not.

It is part of Bach’s missionary mystery that, according to Tokyo musicologists, his appeal to the Japanese is directly linked to the Jesuit missionary St. Francis Xavier (1506–1552). His introduction of Christianity to Japan failed in the early seventeenth century. But whereas Christianity was then outlawed and its faithful martyred, elements of Gregorian chant had already infiltrated Japan's traditional folk music. That influence remained strong enough to help Bach's work sweep across Nippon more than four centuries later.

There is an intra-Christian irony here. Just as this orthodox Lutheran's music is now luring estranged Catholics back into their churches in France, so it is making new converts among the heathen in the Far East. Masashi Masuda told me how Glenn Gould's interpretation of Bach's Goldberg Variations had first aroused his interest in Christianity. It eventually guided him all the way back to the origin of the Jesuit mission in his homeland. Masuda is now himself a Jesuit teaching Systematic Theology at Tokyo's Sophia University.

As Yoshikazu Tokuzen, the Lutheran theologian, observed, "Bach is a vehicle of the Holy Spirit." And that Spirit just blows where it will.

Uwe Siemon-Netto is the Religious Affairs Editor for United Press International.