It is not known why the Priests choose to stitch their mouths shut, or who they worship. They are capable of using holy magic to resurrect allies and attack enemies from afar, while carrying daggers for close combat. The Priests appear to work closely alongside the Fallen Knights, and may belong to the same religious order as Sir William the Black and The Paladins.
After the Overlord attacks the temple, the Silent Order recognizes him as their new god. This earns him the title "New God of the Mumblers".
When you attack their temple, it is advised that you take care of the Priests first, otherwise, they will revive the Fallen Knights fighting with them. They can do this an infinite number of times.