There's no direct evidence in the comic to support this, but in 3E Deities and Demigods, I believe the Asgardian pantheon is divided into suggested race-based groups, with Thor, etc for Dwarves, and Frey, Freya, etc for Humans. Presumably, Dwarves like hammers and getting hammered, and Humans are into procreating like bunnies. Maybe Rich's world has a similar thing going on, where certain groups of worshippers are culturally predisposed towards particular deities' portfolios.
Pretty much this. A human can worship Thor if he wants, certainly, but he is much more popular among the dwarves. Hel is specifically the goddess of the dishonored dead, which requires a system of honor/dishonor that really only applies to the dwarves and those humans that choose to believe in such things. If Haley died of disease, she wouldn't go to Hel because she wouldn't believe that she had been dishonored.
Originally Posted by Eigenclass
In certain campaign settings, you can be a cleric of a whole pantheon, and this doesn't necessarily influence your alignment. Obviously, unless the majority of the pantheon (or at least those holding the majority of the power) are of an opposite alignment from you, you may have some challenges advancing in the church hierarchy. Even in FR, am I remembering wrong, or is there at least one prestige class that worships the whole Morndinsamman?
Also, this. The Twelve Gods are worshipped as a pantheon, by everyone, including evil characters like Kubota and Tsukiko.