A gods role could change depending on the epithet attributed to the god
Epithet
An adjective that accompanies someone's name, which denotes a quality or characteristic about the individual
For a god, an epithet was a title that accompanied the god's name and specified which aspect of the god was being worshipped
Athena Nike meant victorious
Athena Promachos means who leads in the battle
Athena Polias means guardian of the city
Athena Parthenos means the virgin
The openness of religion about whom to worship for each area of their life created challenges for pious mortals. For this reason, one of the most regular questions when visiting an oracle was "To whom should I worship in order to..."
The multiple roles of gods put pressure on the Greeks to get it right, particularly since the literary view of gods shows them to be vengeful
Another issue of religion was that the pantheon of Greek Gods was not an enclosed entity but rather permeable, with deities joining at various occasions and somewhat unclear boundaries between the gods and demi-gods and the mortals
Epithets do not refer only to different functions fulfilled by the gods, but can also be place-dependent. Even without a panhellenic sanctuary (for example the temple of Zeus in Olympia), gods could be worshipped throughout the country
Louise Zaidman stated "Polytheism as a system may thus be thought of as resembling a nest of Russian dolls"