Coleston the Cavalier wrote:
One thing you might want to take into account is that these annual Hallow spells are just that, annual. Which means that some of these places (like a cemetary) have had this spell used for decades if not centuries. Much of that 1000gps of religious stuff might be statues of holy symbols and such that will remain in the cemetary. The CK might assume that a quick Unhallow spell on such a spot might have somewhat of an uphill battle over "residual leftovers" from all those the Hallow spells. In addition, some of the persons buried in the cemetary will hopefull have had some spell(s) said over them when they were buried, at least in some of the more urban areas.
But Gideon is right, many answers to this question with one for each CK!
I'm thinking along the lines of a plot where there's a local holy day where the priest(s) of the temple bring out some famous relic and parade it around the temple/town square. (I'm thinking a golden bowl) The relic is the 1000gp trapping. A whole bunch of folk traditions have cropped up around the day and the ceremony, so much so that most people -including the junior priests- may not even know that there is an actual purpose to the ceremony beyond worship. The head priest is the one of high enough level to actually complete the spell.
One year, just before the holy day, the priest is brutally murdered, his heart ripped from his chest. The ceremony is still held, but the spell isn't cast because no one there actually 1) knows how to do it, and 2) knows that it was being cast in the first place. After the ceremonies are over, the bad guys steal the relic and profane it in their ceremony (which takes all night) by burning the heart of the dead priest in the bowl. The next morning, the relic is found to be missing (or ruined). A Fear effect covers the temple and (nearly) everyone flees.* That night, at sundown, the zombies rise.
The bad guys' longer term goal is to destroy the town and use the now-evil temple as a place to perform more dark rituals. Maybe summon demons, etc.
*EDIT: Upon re-reading, I see that the spell effect works on your own faith/alignment or everyone, you can't specify opposing alignments. So instead of Fear on good guys, make it Bless or Aid for followers of the cult.