structural:summarization
Conflict with the Anabaptists (1525–1527)

Shortly after the second Zürich disputation, many in the radical wing of the Reformation became convinced that Zwingli was making too many concessions to the Zürich council. They rejected the role of civil government and demanded the immediate establishment of a congregation of the faithful. Conrad Grebel, the leader of the radicals and the emerging Anabaptist movement, spoke disparagingly of Zwingli in private. On 15 August 1524 the council insisted on the obligation to baptise all newborn infants. Zwingli secretly conferred with Grebel's group and late in 1524, the council called for official discussions. When talks were broken off, Zwingli published Wer Ursache gebe zu Aufruhr (Whoever Causes Unrest) clarifying the opposing points of view. On 17 January 1525 a public debate was held and the council decided in favour of Zwingli. Anyone refusing to have their children baptised was required to leave Zürich. The radicals ignored these measures and on 21 January, they met at the house of the mother of another radical leader, Felix Manz. Grebel and a third leader, George Blaurock, performed the first recorded Anabaptist adult baptisms.

On 2 February, the council repeated the requirement on the baptism of all babies and some who failed to comply were arrested and fined, Manz and Blaurock among them. Zwingli and Jud interviewed them and more debates were held before the Zürich council. Meanwhile, the new teachings continued to spread to other parts of the Confederation as well as a number of Swabian towns. On 6–8 November, the last debate on the subject of baptism took place in the Grossmünster. Grebel, Manz, and Blaurock defended their cause before Zwingli, Jud, and other reformers. There was no serious exchange of views as each side would not move from their positions and the debates degenerated into an uproar, each side shouting abuse at the other.

The Zürich council decided that no compromise was possible. On 7 March 1526 it released the notorious mandate that no one shall rebaptise another under the penalty of death. Although Zwingli, technically, had nothing to do with the mandate, there is no indication that he disapproved. Felix Manz, who had sworn to leave Zürich and not to baptise any more, had deliberately returned and continued the practice. After he was arrested and tried, he was executed on 5 January 1527 by being drowned in the Limmat. He was the first Anabaptist martyr; three more were to follow, after which all others either fled or were expelled from Zürich.