Seen on the billboard of a Calgary Church:
"Truth turns sealed caves into tunnels"
Call me a cynic -- or claustrophobe -- but that does't make for much of an advert, really. Either way, you're stuck crawling about in a closed, stuffy space, probably not finding the way out and possibly being stuck going round and round for ever.
Tunnels are dark, damp and usually have multiple false corridors leading off to no place.
If anything, this quote hightlights the one possible true thing: there is no such thing as absolute truth. All truth has shading, false entrys and exits, paths leading to nowhere and often, many frustrating dead ends.
Probably not a great quote to use related to religion.