Cultists speak a language that the non-believers will never understand.
It is of the same origin as idioglossia or “twin language” that twins may develop when language skills are delayed in development.
This should not be confused with Rovian or Clintonian cant that is carefully constructed to be the mirror image of what is being said; e.g., peace means war, “I am for you” means “I am for big corporations,” Democrat means Republican, etc. A Tim Russert or Chris Matthews may not understand Rovianspeak but intelligent people with normal language skills do.