I would have sworn that my players were not paranoid ... but an event in my game last Saturday may have convinced me otherwise. One of the foes they're dealing with right now is a cult to a powerful demon ... but what the demon has done is set himself up as the lost patron god of mankind from an old (false) legend. Many good men and women have been drawn into this cult and are gradually brainwashed into great paranoia until they are prepared to do anything to defend their "church", even blatently evil acts (thus becoming evil worshippers of the demon).
My party stumbled across a low-powered temple to the demon, a sort of "recruiting station" operating secretely in the ancient catacombs of a good temple at an old, historic battlefield (where many famous heroes of the kingdom are buried).
The party first encountered a small group of neophyte acolytes who had not yet been converted. Each of them was good ... heck, they even wore white robes! LOL But the party was suspicious from the start, merely because of the location.
I had slipped one of the party members the secret phrase to let the acolytes know that they too were wishing to join the church ... but rather than infiltrate and learn, my party decided direct confrontation was in order. When the acolytes didn't initiate combat and instead just acted paranoid and afraid the party left, confused. Without being given a reason to attack they didn't know what to do.
Later, they stumbled across the acolytes living quarters. And despite reading several of the acolyte's journals and finding no evidence of evil (just a devotion to this lost god and the peace and end of suffering he would bring to the world upon his return) they still didn't get it. Eventually they found one item ... a Book of Vile Darkness (it was being used to help convert the more stubborn in a more forceful way).
Suddenly THAT was enough evidence! The party went back and slaughtered the acolytes without any resistance (in under a round). I then informed them that those in the party who are good felt a sense of uneasiness ... particularly the cleric ... they began rationalizing.
"Well, whoever owns a vile, disgusting book like that one is obviously evil!" the cleric declared.
"Yeah?" The thief asked, pointing to the cleric's backpack (where the book had been stored until it could be destroyed), "Who owns it now?!?"
--Mark C'sigs