Favor is a numerical value that represents the longevity of a player's relationship with their god. A higher favor number indicates a better relationship.
Currently, favor exists purely for bragging rights and has no game purpose. It automatically accrues the longer one continuously worships a particular god, although it can be increased by performing quests that award favor, as well.
During December 2015 favor was reworked, as part of the new priest jobs and to make way for a new level 37 cleric skill. Characters favor values were dropped down to fit in with the new system i.e. 99 favor became 6 favor under the system.