Monday night's bonus episode of Fringe, "Unearthed," was actually a leftover episode from season one. Though odd continuity-wise, it did have one gem of a scene where Walter has a rage meltdown after being challenged by a Catholic priest.
I love that Walter actually has no idea what he's doing, but he's so angry at the priest that he just lies and says he can fix the woman's daughter. Essentially, it does turn out that the young woman was possessed by the "energy" of a guy whose abused wife had him murdered. Though the Fringies manage to cast him out of the girl, mostly through the use of drugs, he shows up in the body of another recently-dead person at the end of the show.
It was a fairly inconsequential monster-of-the-week scenario, notable mostly for its frank acknowledgment of the main characters' lack of religious faith. Not only do we have this scene with Walter, but later Olivia has a conversation where she confirms that she's "not religious." Fringe certainly has a lot of woo-woo new agey spiritualism in it, but "Unearthed" clarifies that the show's spiritual bent is decidedly not Christian.
The one extremely weird thing about FOX showing this episode now was that it was done without comment. So if you weren't aware that it was an unaired episode from last season, you might have been very surprised to see Olivia's dead partner Charlie wandering around solving mysteries with her.