When Melchior Hoffman was imprisoned in Strasbourg, Jan Matthys took over the Anabaptist leadership role in the Low Countries.
In January 1534, Matthys sent disciples to Münster to declare the city as the "New Jerusalem", and quickly baptized numerous converts, including Bernhard Rothmann.
According to historian Darren T. Williamson, "He based his position primarily on three arguments: first, he argued along grammatical lines, not Greek grammar but Dutch/German.
It is important to note that although Rothmann was technically correct on this point of grammar, it was also as commonly understood that there was a long standing theological exception as practiced by the church, namely sprinkling.
In his Restitution he wrote, "The divine, unquestionably Holy Scriptures which are called the Bible alone have the fame that they are needful and sufficient for teaching reproof, correction and for instruction in righteousness for which purpose also almighty God has given them in order that the man of God be without error and equipped for every good work.
The Christology that Rothmann held was the "celestial flesh" idea of Kaspar Schwenkfeld and Melchior Hoffman (and later of Menno Simons).
No one else belongs in it...The Scriptures richly testify that faith comes from hearing the Word and that the holy church be built only of those who believe.
Rothmann initially opposed the polygamy introduced to Münster by John of Leiden, but would later write in theological defense of the idea.
He was part of the earliest movement, as a disciple of Melchior Hoffman, that laid the foundations of Anabaptism in the Netherlands and northern Germany.