: GURPS implies otherwise. From page 9, religion sidebar:
: The only race displaying a variety of religious
: beliefs is humanity. Several religions based in the
: southern lands have become popular. Obscure cults are
: not uncommon, if rarely found in the public eye. Any
: of the elements discussed above might be found in a
: human religion. One cult of particular note is the
: spider-cult of ancient Muirthemne.
This is a strike against the idea, admittedly...one retort might make use of the fact the Smiths aren't the same as the spider-cult; rather, they're its founders. So a small initial group of Dwarves could have made first contact with the spider-world (and done so in a scientific rather than a religious mode), then recruited a large number of human dupes to form a "cult" which carries out their wishes. In that case the only people who actually worshipped the spider-gods would be the humans, and their secretive Dwarven leaders (who, along with a few human mages, would comprise the Smiths proper) would have a more pragmatic relationship with the other world.
--SiliconDream
