Brethren of the Free Spirit
The Brethren of the Free Spirit were adherents of a loose set of beliefs deemed heretical by the Catholic Church but held (or at least believed to be held) by some Christians, especially in the Low Countries, Germany, France, Bohemia, and Northern Italy between the thirteenth and fifteenth centuries. The movement was first identified in the late thirteenth century.
Source: Wikipedia — Brethren of the Free Spirit (CC BY-SA 4.0)