Imagine yourself in the imposing Grossmünster church in Zurich. This is a sanctuary in transition: the votive candles have been snuffed out, the frescoes painted over, and the wooden statues depicting saints and biblical figures removed. The expansive space echoes with the high-pitched voice of Huldrych Zwingli. In the language of the marketplace, he preaches directly from the text of the New Testament, moving verse by verse through each book, ignoring the centuries-old liturgical order of readings. He insists on the need for a biblical Christianity to complete the Reformation Luther has begun.

The Reformation's most radical moment

Several young men listen with particular intensity. These are George Blaurock, a striking, black-haired man of peasant stock, with no great education but great zeal for reform; the scholarly Felix Mantz, illegitimate son of a clergyman at the Grossmünster; and Conrad Grebel, a well-educated young aristocrat whose mangled hand—relic of a student brawl at Vienna —testifies to an impetuous nature. They share a hunger for reform and a respect for Zwingli, with whom they are studying the Bible in the original languages.

The three friends' blood rises with excitement at Zwingli's radical words—some preached from this pulpit and others confided in private: The tithes paid to the church to sustain layabout monks and nuns can not be supported from the Bible. Those who eat meat during the weekly fast break not a divine commandment but a human custom. Even the Mass—the regular recapitulation of Christ's sacrifice, supposed to bring his real body and blood to the people—is an abomination that should no longer be celebrated.

These men have learned much from Zwingli's teaching. But like others among the townspeople who support Zwingli's proposed reforms, they are becoming increasingly dissatisfied with his approach and his progress. Why, they ask, does he dither with the Council, seeking a moderate road to reform, when the Bible so clearly and directly contradicts so many of the church's inherited practices and teachings? Why, bowing to conservative pressure, has he failed to fulfill a promise to abolish the Mass on Christmas Day, 1523?

Zwingli's protégés have concluded that baptism as ordained and practiced in the New Testament is not an automatic conferral of grace, but a sign attached to faith, to be administered upon confession of sin and profession of faith. Surely the sprinkling of some water and the muttering of a few words do not a Christian make! And look at the results: in a state and a church where every person born is baptized in infancy, thus assumed to be Christian, the church (it seems to the radicals) has become nothing more than a social club filled with slackers and sinners.

On January 21, 1525, these young men come to a new understanding of faith and grace in baptism while worshiping in a home near Zurich. Convinced of the need to profess faith and to repent of sin, the impetuous Blaurock asks Grebel to baptize him. Grebel obliges, pouring water over his friend's head in the names of the Trinity.

Into the lion's mouth

Blaurock and Grebel understood that by their act, they were making themselves outlaws in church and society. For over a millennium, since the reign of Emperor Constantine, all Christendom had believed that civic and religious community were indissolubly linked by God. When the Swiss brethren instituted adult baptism, daring to separate church and civil government by declaring that the only true church was a church of gathered believers, they would of course raise the ire of the established order.

But even these first zealous Anabaptists ("re-baptizers"—the term of reproof used by their enemies) could not have foreseen the magnitude of the ensuing persecution.

The purge would start almost immediately at the hands of their teacher, Zwingli, and the Zurich city council, and by the end of the 16th century would wipe out some 2,500 of their brethren in the Low Countries—by burning, drowning (fitting, felt their persecutors, for those who insisted on baptism by immersion), and cruel tortures.

The violence would intensify quickly as Anabaptist teachings were implicated in the bloody Peasants' War of 1524-26. And it would intensify again in 1534, when a group of militant radicals with Anabaptist links gained control of the city of Münster. Under assaults from without, events in the city turned both bizarre and bloody. Innkeeper Jan of Leiden declared himself "King David," instituted polygamy, and began purging the city of opponents.

Severe persecution quickly deprived the Anabaptist movement of some of its abler leaders such as Mantz and Michael Sattler. Grebel died of disease. The confusion of persecution and loss of skilled leaders slowed the formation of cohesive theological statements or ecclesiastical structures for Anabaptists.

Many of the movement's leaders, like the black-haired peasant Blaurock—called "Strong George" and a "second Paul" by followers—came from and cared for the common folk, exemplifying the Anabaptist article of faith that it is the simple and the poor in spirit, not the learned and famous, who are given the gift of understanding God's kingdom mysteries.

But their zeal and love was not always matched by theological or organizational acumen. A preacher would come into town, preach the message of a Bible-based, gathered church, and move on. Converts often came together to form churches on the barest framework of teachings.

In February 1527, several Anabaptists met at Schleitheim, on the Swiss-German border, to bring cohesion to the movement. There they agreed to the "Schleitheim Confession." Michael Sattler, the Benedictine prior-turned-Anabaptist who helped to shape this document, was burned at the stake in May that year for his role.

The Schleitheim document lists seven points of agreement, namely: believers' baptism upon confession of faith; the practice of mutual church discipline (the ban); the Lord's Supper in place of the Mass; separation from Roman Catholic and Protestant churches; the role of ministers ("shepherds"); rejection of violence ("the sword"); and rejection of oaths.

A man of unity

In January 1536, a year after bishops and Protestant authorities suppressed the Anabaptist kingdom in Münster, a Dutch priest in the rural Frisian village of Witmarsum sought baptism from a small circle of Anabaptists who were pacifists. Of Frisian peasant stock, Menno Simons had become a priest at 28 in 1524. Like many rural and small town priests of his day, he had very little theological training. Nonetheless, he was a man given to careful thinking, and in his first year of priesthood, he had begun to have doubts about the doctrine of transubstantiation.

Soon after, Menno had heard of a man who was beheaded for being re-baptized, and the Frisian priest had begun to study the Bible on infant baptism. Baptism, he had concluded, could not cleanse infants from original sin. Nor could he find anything in the writings of Luther and other infant-baptizing Reformers to change his mind.

Finally, the claims of Anabaptism faced Menno with particular force in April, 1535, when a close relative died in a Münster-related riot. Though he found them fanatical and mistaken on some points, they also led him back to scriptural truths. And so he "prayed to God with sighs and tears that He would give to me, a sorrowing sinner, the gift of His grace" and a clean heart. Thereafter he identified openly with the Anabaptists, leaving his comfortable clerical life and traveling (under constant threat of death) to strengthen and unify the movement's scattered congregations. Dying of natural causes in 1561, Menno left behind a more clearly defined Anabaptist movement that became known by his name: Mennonites.

During the 17th century, Dutch Mennonites faced a new and unwanted problem: prosperity. This they began to achieve under a new, more tolerant regime after Dutch independence from Spain. Fearing that newly respectable Mennonites would forget their radical origins, one minister tried to stir up new vigor. Tieleman Jansz van Braght compiled stories of Dutch, Swiss, German, and Austrian Anabaptist martyrs and in 1660 published them in a book known as the Martyrs Mirror. In the 18th century the Mirror became an influential work connecting Dutch and Swiss Mennonites to the Amish and Brethren.

Tailor-made reform

After 1670, new internal tensions arose in the wake of a Bernese edict ordering Anabaptists to join the Reformed Church or be expelled. In response, some Anabaptists fled Switzerland for Alsace and the Netherlands. But others chose to stay and worship occasionally in the Reformed churches, even allowing their children to be baptized. In addition to appeasing local officials, this conformity guaranteed that children of Swiss Anabaptist families could legally inherit land.

One Anabaptist minister, an Alsatian tailor named Jakob Ammann, sought to tighten church discipline. He sought to return them to the old practice—approved by Menno Simons—of "shunning" unrepentant members by avoiding all social contact with them until they repented.

Another minister back in Switzerland, Hans Reist, objected to Ammann's teachings. In 1693 a series of rancorous meetings took place in Switzerland, during which Ammann excommunicated Reist and others who followed his laxer teachings. Believing that Mennonites were now turning their backs on the humility and simplicity of the earlier movement in order to fit in and advance in society, Amman insisted male members wear untrimmed beards and eschew "haughty clothing." (One can imagine that as a tailor, he had seen at close hand the inordinate pride some took in keeping up fashionable appearances.)

News of the split soon spread to Mennonites far and wide, from the south Rhine to Holland and North Germany. In Alsace, Mennonite leaders agreed with Ammann that the compromises of a newly comfortable Mennonite community threatened their very souls and the purity of the church for which so many had died 150 years earlier.

Reist's fellow believers in Bern, however, were living in far from socially compromised ease. They faced enough external threats without dividing the church from within through legalistic requirements. "Nor," as historian Steven M. Nolt puts it, "were they keen to receive lectures on faithfulness from those who lived in relative safety outside of Bern." Eventually Ammann's group broke fellowship from Reist's group, taking the name "Amish."

A third branch

Meanwhile, the 17th-century Pietist movement within the Lutheran and Reformed churches planted the seeds for a third branch of the Anabaptist tree, the Brethren. Seeking to complete the Reformation's reform of doctrine with a reform of devotion, the Pietists read the Bible and pursued godly living in small groups that made the authorities nervous enough to ban them in several territories.

Although most Pietists had preferred to reform their Lutheran and Reformed churches from within, some soon began to question the form of the church itself, rather than seek its renewal. For example, the Pietist historian Gottfried Arnold (1666-1714) compared Protestantism to the ancient Christians and found the Protestants lacking. Arnold's writings inspired others to separate fully from Protestantism. Some of these separatists sought refuge in tiny territories offering limited religious toleration.

In Schwarzenau on the Eder River, separatists Alexander and Anna Margareta Mack looked to Arnold's accounts of early Christians and to the New Testament for models of the church. Mennonite writings such as the Martyrs Mirror also influenced the Macks. They felt called to form a gathered church.

In August 1708, eight people went to the Eder River to receive baptism by threefold immersion in the names of the Trinity upon the confession of their faith and repentance from sin. The group also agreed to practice mutual church discipline. They observed the Lord's supper with foot washing, an agape meal ("love feast"), and the Eucharist, consisting of unleavened bread and wine.

These "New Anabaptists," or "Dunkers" were pacifists and rejected oaths. They evangelized energetically and emphasized the joy in discipleship. With their baptism in 1708 the Brethren broke with their separatist friends in Schwarzenau.

Although not members of Mennonite congregations, the Brethren were spiritual kin to the Anabaptists who had been awakened in Pietism. In the 18th century, they would join their Mennonite and Amish counterparts in a great migration to America.

Chris Armstrong is managing editor of Christian History & Biography. Jeff Bach is associate professor of Brethren and historical studies at Bethany Theological Seminary in Richmond, Indiana.