"Need have no fear indeed," Gaven says after being bathed in the holy fire.
Duran and Gaven look to see if the trap door can be opened and closed from the inside of the passage. They discover that the lever does precisely that. The lever inside the trap door also seems to trigger no holy fire.
With the mechanism of the trap door figured out, Gaven considers Oloc's suggestion and turns his attention to the graffiti once last time. First the cleric rubs a little bit of holy water on the red markings; then he tries a mix of holy water and the liquid from the font. In both cases, the reaction is similar to the one before – an angry hiss, but no luck in removing the markings.
Before heading down into the darkness, Oloc empties his waterskin and fills it with the water from the basin. Duran follows Oloc, as does Gaven. Between the three of you, you empty the basin.
The party decides to leave the mule, Sophie, the two porters at the top of the stairs. Stan is also assigned to guard them, since, being a fervent believer in the light, he can likely use the lever in the altar if need be.
The remainder of the party descend into the darkness, Oloc holding a torch so that all may see.
At the bottom of the stairs, you find yourselves in a very long tunnel heading north. The tunnel is 10' wide, and featureless, but lined with the same smooth stone as that of the church above. After about 100' or so, the tunnel opens out into a 30' x 30' chamber.
Horizontal stone recesses are set into all the walls, going all the way around the room, from about 2' above the floor, all the way to the ceiling, some 10' up. Each recessed shelf has about 2' of horizontal space, into which have been laid the bones of dozens and dozens of skeletons. The remains look very dry, brittle and old.
Gaven recognizes this immediately as the church's catacombs. The skeletons here clearly belong to the brothers and sisters of the Light who once served in this church.
Engraved in the center of the floor is the symbol of the Light.
Also covering the floor, in the northeast and northwest corners of the room, are shallow puddles of what appears to be the same red substance used to trace the graffiti in the church above. The substance is in a slowly bubbling liquid form, and it appears to be oozing up from the spaces between stones in the floor.
Otherwise, you note exits to the north, west, and east, in addition to the opening to the south, through which you entered.