Anabaptistry

A place where Anabaptist worship or practice occurred; alternatively, the practices and doctrines characteristic of Anabaptists collectively.

From 'anabaptist' + '-ry' (suffix denoting place or practice). Similar to how 'monastery' is a place of monks and 'archery' is the practice of archers, anabaptistry could mean either a location or the collective behaviors of the movement.