Something to this effect?
[X] Public knowledge of the matter will be the bringing of the House of Black and White into compliance with Imperial Law, which is fully true, at this time they are committing no ongoing breaches by omission or otherwise. The Faceless Men do not traditionally worship any proscribed against Gods, but their presence is integral to drawing power from the Faceless Gods' primary domain. Exclusion is more dangerous for reasons which would be cognito hazards in the mind of the uninitiated or untrained to reveal publicly.
-[X] Restricted (Scholarum, Inquisition, etc. but not necessarily Forbidden) details on the the doctrinal practice of idolatry to even proscribed against deities known to inhabit the Lower Planes by the practitioners of magic within the Faceless Men is that it is not true worship, identified by the fact that they worship a Concept of Death and draw power from a universal pool from which all deities with the domain do contribute, a perilous path to power that essentially only guarantees a high likelihood that the very same order that trains such mages has been responsible for eliminating rogue elements for centuries... thus far to terrifyingly good effect, the details of which are startlingly similar to the same manner of the well documented drawing of power from the Concept of Law many in the Scholarum now make use of, most well-known of all being Malarys. Anything else about this arrangement, I.E exact details of how it shakes out or how the class works or really what the true threat could do to those deities if they weren't involved in the system (Void-taint) is strictly Forbidden (Tier 3) knowledge, generally only known by Inquisitors, Lord Inquisitors, General Commissars and other agents of the Crown.