The Unspoken Pact

The deities are quite distant from their followers in the Land of Mists, and outlander priests and paladins will notice this void of communion even as they still receive their powers. The Ravenloft Player's Handbook (p.64) and Ravenloft Third Edition (p. 50) discusses some theories why this phenomenon occurs and some of its ramifications.

The Unspoken Pact is a theoretical agreement between the various gods and the Dark Powers, allowing the former to continue empowering their priests in the Demiplane of Dread, at a price of not being able to directly influence those lands or counsel their followers.