They're getting small amounts of corruption from stealing stuff, being wounded by corrupting monsters, using corrupting magic left and right, visiting corrupting locations and so on, but over the course of two-thirds of the campaign only one character got anything out of literally pooling corruption from another player into himself and that was only -4 character points worth, and everybody else hasn't even had -1 added to date.
Im considering using
This alternative system I'm working on instead because of the short-form nature of this campaign.
Every other character pays in corruption and fright checks for using any supernatural power, but the faith based character can use divine guidance, smite stuff with blessed weaponry, stab ghosts and stuff with no drawbacks, sure he paid for them with points but hes getting so much more out of those points than the other players.
So far they havent encountered any, they bypassed the only encounter with ones that have hearing-based mind control, but you're right maybe a few more crafty enemies might be a good idea.