It suggests that the ancient Greeks firmly believed in Gods, that their wrath was expressed through nature and that the Gods did harm to humans through harsh storms that scared them to death and destroyed their possessions (In this passage, their ships). However, although their punishment was tough, it was not everlasting because following two days of destruction, the sky was not dark anymore, and "a third Dawn came with ringlets shining", which may suggest that they believed Gods were compassionate as well.
