So, I was reading Lean Times in Lankhmar this morning. They talk about a long line of temples, and how various Gods in Lankhmar move up and down the street, and I asked myself "Why? Why do they believe in all of these, and why does this cultural standard persist? Why are new ones allowed in and why do old ones go?"
Then it occurred to me, thinking about it in a different way. Their donations and the religious sermons they receive, functionally, are training in passions. Passions that actively give them something - essentially a swiss army knife for skills. Passion allows Fafhrd to convert many, and increase the religions coffers. He uses his passion to augment his storytelling (or perhaps he uses his storytelling to augment his passion, as Isaak starts taking on a northern style). Pulg used his passion to make the disguise for Fafhrd. The votaries, of course, use their passions to elicit donations, but I think that this exchange is less about persuasion to give money, and more about increasing a passion so that they will, or so they can use it against them to get the money.
Anyhow, just something I was thinking about. I would be hard pressed to find a setting more suited to Mythras than Nehwon