Written by: Ted Vial
The Reformers immediately faced challenges. Having argued that scripture was the final authority in matters of belief and practice, elevating it over human institutions (like the papacy), the Reformers trusted that the same Holy Spirit who inspired scripture would lead the elect (saved Christians) to a correct interpretation of scripture. The Catholic Church predicted that without institutional authority, people would not agree on what scripture meant, and the result would be schism and anarchy. On this the Catholics turned out to be right.
Zwingli had been pushing for reform based on the model of the Church found in scripture. He had argued against the use of images in worship, fearing that images led to superstitious and magical beliefs, when worshipers should instead rely on the promise of forgiveness of sin found in the Bible. In particular he wanted to abolish the Mass, which Roman Catholics frame as a recapitulation of Jesus' sacrifice performed by priests as an offering to God, and replace it with a commemoration of the Last Supper and the crucifixion, which was the act that had already accomplished the forgiveness of our sin.
At the Second Disputation in October 1523, the City Council of Zurich agreed with Zwingli that the Mass should be abolished and that the use of images in worship was not scriptural. Zwingli was an astute enough pastor, however, to understand that too rapid a change in ritual practice would upset rather than reassure his parishioners and would work against the ongoing process of reformation. He was content to allow the City Council to set the schedule of changes in the Lord's Supper.
Zwingli was immediately opposed by a group of people more radical than he, who labeled him a "half-way man." Conrad Grebel (ca. 1498-1546), George Blaurock (1491-1529), and Andreas von Carlstadt (ca. 1480-1541), who earlier had hailed Zwingli as a hero, now turned on him. They argued that the Holy Spirit had already abolished the Mass, and it would be against God's will to leave the pace of reform in the hands of the City Council. They argued that correct performance of the Lord's Supper required strict adherence to the description found in the New Testament, down to details like using unleavened bread. (Zwingli argued that certain key beliefs such as justification by faith were non-negotiable, but other matters, such as type of bread to be used in the Lord's Supper, could be left to the choice of individual congregations.)
Further, they argued that since justification was by faith, only those old enough to understand sin and redemption could be baptized. They rejected infant baptism (Zwingli maintained this practice with, he felt, good theological and scriptural warrants). Believing that their own infant baptisms were not valid, they "re-baptized" each other. For this reason their opponents labeled them Anabaptists (re-baptizers). Finally, their biblical literalism led them to believe that Christians could not participate in several key civic duties, like swearing oaths (and thus appearing in court) and joining the military (Jesus sounds a lot like a pacifist in the Sermon on the Mount). Zurich saw them as traitors as well as heretics, and quickly moved to imprison or kill them. Because of this persecution some of their followers came to the "New World," bringing with them Anabaptist denominations. Menno Simmons, founder of the Mennonite Church, is another prominent Anabaptist.