Yeah, but remember who we're talking about here. This is the Joker - he's the guy who other villains tell stories about when they want to scare each other. He's a bogeyman even to other bogeymen. Anyway, even if there IS a special order of priests for that purpose, it's likely that they would largely be sent to places like the Slab or Iron Heights - places that are specifically designed to house superhumans. The Joker, dangerous and crazy though he is, is basically a normal human being - he doesn't have superpowers or anything else to set him apart from the rest of humanity except for oddly-colored skin and hair. (In fact, that's one of the things that makes him so scary - that a normal person CAN accomplish all the horrible things he's done.) If memory serves, he's in Blackgate here, the same prison they send the Penguin to. They probably have a regular chaplain in-house - there would be no need to keep the special sort around, since they get so few of the Joker's calibre. This sort of scene has been done before, actually - way back in the Golden Age, the Joker, tired of having to live on the run, turned himself in to the cops and was executed for his crimes. (He'd worked up a special serum that his underlings could resuscitate him with, allowing him to live as a free man having paid the price for his crimes, the sly devil.) Anyway, prior to his sentencing, there's a scene where the Joker is cheefully reciting a long, long list of his past crimes to a policeman, who is looking awfully sweaty and jittery and thinking to himself 'Won't he EVER stop confessing...?' And apparently this has been going on for a WEEK!