Marvelverse vampires seem to be repelled by 'faith power' - I remember in Dracula's early X-men appearance, crucifixes worked for Nightcrawler but not for Wolverine, and Kitty couldn't use a cross but could use her Star of David, etcetera. A goddess might be holy, but it sees logical that she wouldn't have a real religious belief in herself, the same way a mortal who worshiped her would.