For centuries, one church ruled religious life in Western Europe. From the pope in Rome to village priests, the Roman Catholic Church exercised complete spiritual authority and did not tolerate dissent.

By the 1520s, however, opposition was rising. With the emerging technology of printing, new ideas spread quickly. Reformation fever, ignited by the German priest Martin Luther in 1517, took hold. Reading scripture in new ways, reform-minded people challenged traditional practices and theology.

The most radical voices — the dissenters who demanded the greatest change — were the Anabaptists.

Believing, as Luther said, that “a simple layman armed with scripture is greater than the mightiest pope without it,” the Anabaptists challenged the primary symbols of Roman Catholic authority: the sacraments.

These sacred rituals — baptism; the Eucharist, or Communion; confession of sin and doing penance; receiving last rites when near death — were considered necessary for salvation.

Baptism was thought to be especially powerful. Performed on infants, it was understood to cleanse a child of sin — not symbolically, but literally.

Was infant baptism biblical? According to Catholic theology, it did not need to be. Church tradition was sufficient.

But Anabaptists insisted scripture was the sole authority, and they found no basis in it for infant baptism. In fact, just the opposite: “The one who believes and is baptized will be saved” (Mark 16:16). “Repent and be baptized” (Acts 2:38). An infant could not believe and repent.

Believers baptism — first practiced by Anabaptists in Zurich, Switzerland, on Jan. 21, 1525 — was more than just an attempt to challenge the authority of the church. It went to the core of the Anabaptist understanding of what it meant to be Christian. Faith was not something one was born with. Christian identity came about by faith in Jesus.

The Anabaptists joined a host of others reexamining scripture and coming to new conclusions. But other Protestant reformers found it difficult to imagine not baptizing infants. None was willing to challenge infant baptism in quite the same way. Anabaptists stood alone.

This made them heretics, subject to punishment by the state, because the church’s spiritual authority was connected to civil authority. Through baptism, one became a part of the church and a citizen of the state. One’s baptismal record was like a birth certificate. To be unbaptized was to be undocumented.

The close relationship of the church and the civil authorities formed a Christian kingdom, or Christendom. The state handled civil life; the church offered eternal life. Each ruled its sphere and supported the other.

Anabaptists denied the church’s claim of spiritual authority and challenged its relationship to civil authority. Anabaptists were among the first to see a need to separate church and state. They declared their true citizenship to be in the kingdom of heaven.

Civil and religious authorities throughout Europe moved quickly to quell the heresy. Thousands of Anabaptists were imprisoned and put to death by burning at the stake, drowning in a river or beheading.

Despite the persecution, Anabaptists continued to meet, often in secret. They shared the bread and wine of the Lord’s Supper, viewing them as symbols of Christ’s body, offered for their salvation.

Here again they challenged Catholic understanding: the Eucharist as a sacrifice in which the bread and the wine miraculously became the actual body and blood of Christ. For Anabaptists, the Lord’s Supper was a memorial meal.

Anabaptists believed the core of Christian faith was expressed in a life of discipleship. Following Jesus as a disciple meant living as Jesus did. The Gospels’ accounts of Jesus were especially influential for sorting out what that meant. As a result, the Anabaptists became radical Bible readers who tried to put into practice what they read in scripture.

When Jesus said, “Love your enemies” (Matthew 5:43), Anabaptists read this as a literal command. Many refused to arm themselves against those who threatened their lives or property. To kill in the name of Jesus, the one who came to bring peace, was unthinkable.

Their refusal to fight against so-called enemies was another threat to civil authority. How could Anabaptists be trusted if they refused to bear arms? The Anabaptists said they respected civil authority but owed their primary allegiance to Christ alone.

Anabaptists today continue to call each other to a life of discipleship and to resist finding security in political allegiances. They seek to live at peace with neighbors and practice love of enemies. They place special emphasis on voluntary church membership and believers baptism. In the spirit of the 16th-century Reformation, they look to the Bible as the sole authority for faith and life.

Born as a movement of religious reform, Anabaptist renewal continues. Today, in addition to members of Anabaptist churches, Christians from other traditions are drawn to Anabaptist theology and practices. The witness and message of 16th-century Anabaptism in Europe inspires followers of Jesus around the world in the 21st century.

Valerie G. Rempel is director of accreditation for The Association of Theological Schools. She formerly was J.B. Toews Chair of History and Theology at Fresno Pacific Biblical Seminary, the U.S. Mennonite Brethren seminary.