The transformative — and ironic — achievement of Martin Luther’s Reformation. (Peter Endig/European Pressphoto Agency)
Ed Simon is an editor at Berfrois, a staff writer for The Millions and author of"America and Other Fictions: On Radical Faith and Post-Religion."

A half-millennium ago, Western Europe saw its first mass-media revolution when a man who was simultaneously learned and earthy, bawdy and bigoted, humane and intolerant challenged church authority and launched an unprecedented religious movement: the Reformation. Martin Luther created a distinctive new brand of religion, using his canny mastery of the new media technology of his time — Johannes Gutenberg’s printing press — to transform a small theological rebellion into a veritable revolution that altered Christianity forever.

According to legend, 500 years ago on Oct. 31, Luther nailed his “95 theses” to the Castle Church door in Wittenberg, Germany. Today, celebrations are happening around the world and across the denominations he helped create, with even the Roman Catholic Church — the very church he challenged — commemorating this anniversary.

But in the midst of these celebrations, we must be careful not to overlook the modern paradox of Luther’s rebellion: In many ways, it was both a triumph and a failure. He challenged church hierarchy with his concept of a “priesthood of all believers” — an idea that today has undermined his other theological arguments.

Luther led a revolution by challenging certain aspects of medieval Catholic theology. He initially limited his criticism of Rome to practices such as the sale of indulgences — money that believers paid to the Catholic Church on behalf of family members who were in purgatory (a kind of waiting room for souls not quite ready for heaven). But ultimately, his challenge to the church would go much further, with the development of a full-fledged theology that emphasized scripture over ritual, a reliance on the Bible alone as an authority and a belief that salvation is granted only through faith, not good works.

Not least of Luther’s many criticisms of the Catholic Church involved the latter’s interpretation of Communion. Catholics believed in the literal transformation of a Eucharistic wafer into the body of Christ and of Communion wine into his blood. This process that Catholics termed “transubstantiation” Luther called “a monstrous idea.” Rather than viewing the sacrament as the actual transformation of wafer and wine into Christ’s body and blood, he argued that Communion was about the individual’s spiritual relationship to Christ. For Luther, a transformation of a sort was still involved, but it was not a material one.

This new attitude toward Communion sparked larger debates about practices and beliefs in Christianity. Luther advocated the primacy of the individual in being able to interpret scripture, famously calling for a “priesthood of all believers.” But he assumed that proper interpretations would lead to the same theological conclusions for others as for him.

Inevitably, this was not the case. Individualism, once unleashed, led to fracture, as new reformers found innovative interpretations that challenged Luther’s. For example, in Switzerland, Ulrich Zwingli led a more radical reformation of his own, arguing that the Eucharist was purely symbolic and that no transformation of any manner took place. Thus, a new interpretation of Christianity was born, one that was in some ways as divergent from Luther’s theology as Lutheranism was from the Catholic Church.

Today these debates can seem distant. But we are still very much living in the wake of Luther’s revolution. From that schism initiated at Wittenberg, Western Christendom was split, and in the aftermath we’ve moved from one overarching church to more than 30,000 denominations (and counting), with close to 1 billion Protestants constituting almost half the Christians in the world. When Luther hit hammer to nail 500 years ago, he prayed for the reform of the church, but he wouldn’t have desired the fracture that followed.

Nor could he have anticipated the surprising manner in which Reformation theology would develop across denominations. Today Catholics and Protestants are officially divided on questions about Communion (among other issues), but according to the Pew Research Center’s 2010 U.S. Religious Knowledge Survey, more than 45 percent of American Catholics “do not know that their church teaches that the bread and wine used in Communion do not merely symbolize but actually become the body and blood of Christ.” And so, 500 years later, almost half of Catholics unknowingly side with Luther’s more radical Protestant adversary. But this is not a one-sided sectarian victory, since a Pew poll this year revealed that more than half of Protestants believe that salvation is merited through a combination of both faith and good works — a distinctly Catholic position.

Conservatives on both sides might argue that these discrepancies in orthodoxy are due to an increasingly secular generation’s poor religious education. But maybe there is a more optimistic interpretation. As Catholics embrace Protestant positions and Protestants adhere to Catholic ones, perhaps this cross-pollination speaks to our “post-theology” moment, which represents a new denominational openness.

If so, then that openness has been hard-won, and we should be thankful for its emergence. The aftermath of the Reformation saw unprecedented religious violence in Europe, as well as divisions that seemed as if they couldn’t be sutured. Yet it was in part that creed of a “priesthood of all believers” that allowed for an individualism that helped heal the wounds inflicted in the early 16th century.

For all of Luther’s successes, the ultimate legacy of the Reformation may be its own obsolescence. A “priesthood of all believers” implied equality, with individuals each interpreting scripture in their own way. Though Luther never offered anything close to a full-fledged defense of religious freedom, which wouldn’t happen until the writings of radical reformers in the centuries to come, his powerful language about an independent conscience helped lay its groundwork.

The Reformation marked the beginning of a new era that is only now arriving at its full fruition, an era best characterized as “After Theology.” Freed from the strictures of orthodoxy, individuals can now mix and match theologies as suits them. What remains is individuals’ endless, creative, imaginative ability to construct their own faith, by their own dictates.

The legacy of being freed from theology means we can invent our own faiths, so that in 2017, we can, ironically, proclaim that we are all Protestants. There are Catholic Protestants, Jewish Protestants, Muslim Protestants, atheist Protestants, sometimes even Protestant Protestants — Protestants all. How could it be any other way with every man and woman a priest?