You just need to speak to the diety prophet/represenative of your chosen deity to get the quest line started. The Rallos Zek represenative is hanging out on top of the rock slope leading down to the path that goes to GFay in Butcherblock Mountains.
how about diety quests for warlocks? i've been asking for a week now on my server but nobody seems to know which god is good for poison and diesease and where to start it. :(