the church of Pity lore (in case you don't watch ren's POV of cowboy smp!)
The bandits that attacked Pity specifically went for the church, targeting what was given the vague descriptor of "valuables." When they didn't find anything, they murdered the preacher inside and left. It is implied that the real valuables (whether it was objects, books, or bodies wasn't specified) are buried underneath the church.
The new preacher (Ren) took the old ones' place, assuming a fierce rivalry with the mayor (Oli) along with his duties. The role of preacher to the church of Pity seems to be far more protection-oriented than teaching-oriented-- almost nothing to have to do with being a preacher at all. Almost no one shows up to hear sermons in Pity, but Preacher is always equipped to defend the building. The mayor even went as far as to say "Damn! You're strong! Were you always a preacher, Preacher?" in the first episode, to which Preacher did not respond. Offhandedly after slaying a spider he remarked, "I have been called Monster Hunter before. But not in this town," and continued on. When Sausage admitted to murder during confessionals, Preacher said, "These are actions I cannot judge. I had a past before Pity." As expected, he didn't respond to any further queries.
The mayor seems to know that something is buried under the church that the preacher is hiding, sometimes sneaking behind the preacher's back to attempt to dig. Preacher and False are on patrols together to make sure he doesn't get there, but False doesn't know why.
It was also the mayor who invited everyone to Pity to dig for gold, inviting them to dig anywhere and everywhere they liked. Preacher hated this, saying he "can't trust the ambitions of any of the arrivals." However, due to the newcomer Pyro, we know that bandits, the mayor, and the ghosts of Pity are not the only ones looking for the riches.
It's also the government.