You don’t HAVE to define all aspects of the reality of a game world through rules, but if it’s the kind of thing you enjoy you CAN.
Any character that worships a deity may take the UnAppeased quirk in place of a single favored class bonus.
When you are in a settlement that worships the pantheon your deity is in, and you are at a location other than a church which is strongly tied thematically to one of your deity’s Areas of Concern, and that location does not have some acknowledgement of your deity (a shrine is most common, but even working in your deity’s symbol, colors, or favored weapon or animals in a noticeable way qualifies), you gain a minor advantage against those within that location engaged in its associated activities. If you make an attack roll and miss, you may reroll the attack. If you force a foe to make a saving throw and it succeeds, it is force to reroll. Once a single missed attack hits or a single successful save fails, you no longer benefit from this quirk for the rest of the day.
Because of this, even in non-evil settlements, court houses and legal buildings often a mace, serpent, or at least red and black colors worked into an area, to appease Asmodeus who has contracts as an Area of Concern.