How about a god of Treachery masquerading as a more benign deity? For example, a god worshiped by subordinates and functionaries called things like The Dutiful Clerk or The Necessary Servant--never a personal name, only a job description indicating stalwart servility--but who (known only to the inner circle) is actually the god of usurpers, traitors, and the amorally ambitious? Not only would a congregation of menials and hirelings be the perfect cover for a cabal of infiltrators and betrayers, but the very act of duping the loyal and dedicated masses into worshiping a god of betrayal under false pretenses is itself a sublime act of treachery.
