OK, so I leave for a couple of weeks of paying to live like a homeless person (read: I've been on a camping vacation with my family) and I come back to this monolithic structure being raised in your living room! I even completely missed this entire thread.
Now, it's just several shades of awesome, and I'm sure we'll have some interesting games in there. It having exits an all sides is probably a good idea for playability (although probably not the most defensible location for any survivors to hole up in
).
And making sure it can be used for different denominations is also a good move; I can see this thing working with anything from historical, to modern, to fantasy, to post-apoc to even 40K!
I had to look it up, but it immediately reminded me of this eighties apocalyptic film, Prince of Darkness, where apparently the remains of the antichrist were stored in some sort of cilinder, and as the container started to fail, all the homeless people hanging around the church turned into zombies, while the people inside (priests and scientists) tried to keep them out, while at the same time trying to keep the devil from crossing over into this world.
Your church would be just the terrain to replay that
I can't wait to see it in the foam myself...